Vendors were devices used to distribute weapons, weapon modifications, gadgets, ammunition, and armor; accepting bolts or Raritanium as payment. Vendors were created and distributed by various corporations and factions, and are placed throughout the universe and used throughout the Ratchet & Clank series. They usually come in the form of a computer, which can be opened up into a menu where the aforementioned commodities may be purchased. The menu usually depicts its goods using icons or other visual aids, with short descriptions of the product to accompany it.
In-game, vendors are typically placed in areas that serve convenient or useful to Ratchet or Clank. They can be located near a landing site where Ratchet's current ship is located, as well as in some continue points, and preceding boss fights or brawler challenges. In Ratchet & Clank Future: Tools of Destruction, being near a vendor would replenish Ratchet and Clank's health.
Ratchet & Clank
The first vendor to appear in the series was a blue Gadgetron vendor, accompanied by a video transmission of a vendor tradesman to encourage customers to buy weapons, and sometimes to expedite the process. The vendor itself appeared as a segmented box with a large Gadgetron "G," with the word "Gadgetron" revolving around it. The menu was divided into six separate screens. The top screen contained a scrolling message describing the product (though if left idle would also contain ads and gags such as "Eat at Joe's!" or "Help! I'm stuck in this box!"). The bottom screen contained weapon icons which could be selected to manipulate both the top and left screen, the latter of which contained an image of the respective product. The right screen contained the video transmission of a vendor tradesman who would repeat a set of lines. Below the left and right screen were "Buy" and "Exit" options respectively. In the middle of the menu was a rotating model of the selected weapon.
There were also two Gold Weapons room which served as vendors for gold weapons. One was located at Gemlik Base, with five weapons for purchase, and the second one was located at Veldin, with ten weapons for purchase available after beating the game.
During Ratchet & Clank: Going Commando, Gadgetron had been trounced in the Bogon Galaxy by MegaCorp. As such, MegaCorp vendors (also known as MegaCorp Weapons Emporiums ) were used, instead of Gadgetron's. MegaCorp vendors had a more futuristic design compared to those distributed by Gadgetron, with a cylindrical mainframe in the center of the vendor and four screens connected by a thick cable encompassing the mainframe. Accordingly, there was a large "M" for MegaCorp above the base, with a revolving "MegaCorp" around it. The menu also changed to a more futuristic design, having a holographic blue color with an aesthetic menu arrangement, and was not accompanied by a tradesman or other personality. Although MegaCorp had all but cornered the market in Bogon, the planet Barlow had a still-functioning Gadgetron shop where Ratchet was able to recover or purchase weapons obtained in his previous adventures in the Solana Galaxy. MegaCorp also introduced to the series armor vendors, which sold units of armor. They looked very similar to the MegaCorp weapon vendors, but had yellow lighting accents and were slightly larger. Armor vendors are notably rarer in this game, and each time an armor vendor is found, a new set of armor becomes available.
In addition to MegaCorp weapon vendors, Slim Cognito had a ship shack vendor inside which he illegally made modifications to his customers' ships, namely Ratchet's Star Explorer, in exchange for raritanium. He also owned various weapon modification vendors.
Up Your Arsenal
In Ratchet & Clank: Up Your Arsenal, Ratchet and Clank returned to the Solana Galaxy during the Tyhrranoid invasion, and as such, returned to using Gadgetron vendors and products. However, while identical in form factor, the vendors's colors were changed to orange for an unknown reason (whereas previously they were blue). The menu also changed, albeit similar in design to the MegaCorp vendor menus but was now orange-colored as well, and its arrangement was simplified. Armor vendors look more like capsules rather than weapon vendors. The only armor vendor in the game is located in the Starship Phoenix in the room on the left of the weapon vendor. Armors from Going Commando are available in Up Your Arsenal as well.
Gadgetron employee discount
If the player is a Gadgetron employee, i.e. if the player has Ratchet & Clank save data with the Hologuise gadget on their console, he will get a 10% discount on all Gadgetron weapons in Up Your Arsenal. You can scan for save data by selecting the memory card button on the far right in the Gadgetron weapon vendor in the Starship Phoenix.
If you have replayed the game in Challenge Mode, you lose all of your gadgets, so the discount will not be applied. One of your sava datas (it does not matter which) has to have the Hologuise.
The discount does not apply to armor.
In Ratchet: Deadlocked, Ratchet and Clank were kidnapped by Vox Industries and forced to participate in the holovision program DreadZone in the Shadow Sector. During the competitions, Ratchet used DreadZone vendors, which sold weapons and weapon modifications. These vendors were quite different from usual vendors in form factor, somewhat similar to the MegaCorp vendors with their pyramid-shaped base, but colored red and yellow with a holographic screen displaying the DreadZone logo. In addition to weapon vendors, there was a DreadZone combat bot vendor at Big Al's workshop at the DreadZone Station. It was used to upgrade and customize Ratchet's combat bots, allowing him to change their paint job, head style, and weapons.
In Ratchet & Clank: Size Matters, Ratchet and Clank decided to take a vacation and returned to Solana on planet Pokitaru. Being back in Solana, the orange Gadgetron vendors returned to use. The menu had changed a bit with the color background thereof was changed to light gray. Slim Cognito's weapon modification vendor also returned.
Starting with Ratchet & Clank Future: Tools of Destruction and ending with Ratchet & Clank: Into the Nexus, Ratchet and Clank operated in the Polaris Galaxy, which largely used GrummelNet products, and as such, used GrummelNet vendors. There were three different GrummelNet vendors, selling weapons, devices, and armor. Each came with a Grummel clone to assist customers, with the armor vendor Grummel having the mannerisms of an outfit attendant and a virtual dressing room beside it. The Polaris Defense Initiative 1887-Upsilon permitted some number of GrummelNet vendors within proximity of populous civilizations, making them very popular. 
Secret Agent Clank
In Secret Agent Clank, Clank used Agency vendors, disguised as telephone boxes which sells both weapons and gadgets. They sold products for both Ratchet and Clank; those which were intended for Ratchet would have a red background, and would gifted to him in prison.