You *can* check the vendors through the Map tab. Unfortunately, their wares are broken and all of the displayed secondary characteristics (scopes, special abilities, etc) are wrong. On top of that, they don't display the item cost of anything, so there's... room for improvement. On the plus side, as long as you have equipment in your character's inventory, you can also equip it out-of-game... in the browser version. Yeah. Room for improvement. Yeah.