There are three shopkeepers - one in Dodge, one in Empire, and an Indian Trader. Each shopkeeper is a separate store with his own unique items.

The shopkeepers work in a very strange fashion. Each shop will only ever have a total of 10 items. They show you 5 to start with. If you buy one of those 5, you get to see the "second item for that slot". If you buy the second item, then nothing else ever goes into that spot. It doesn't matter how often you come back.

Dodge City
pickaxe $15 - lets you dig for gold
-- item 2 = scalping knife $25
extra health slot $25 - you always need more health!
-- item 2 = more health $40
shotgun speed loader $25
-- item 2 = shotgun speed loader 2 $50
pistol speed loader $15
-- item 2 = faster loader $30
cylinder boring kit $15 (adds damage)
-- item 2 = heavy cylinder boring kit $50 (adds 5 damage)

Empire City
extra dynamite slot $35
ammo belt $30
rifle speed loader $20
-- item 2 = rifle speed loader 2 $45
barrel extension $20 (adds damage)
-- item 2 = long barrel extension $50
quality horseshoes $30 (faster horse)
-- item 2 = premium horse chow $40 (healthier horse)

Indian Trader
hatchet sharpener $30
-- item 2 = extra quiver $50
shotbun barrel choke $30
-- item 2 = shotgun choke 2 $50
premium arrow fletcing $30
-- item 2 = true flight bow talisman $50 (fast and far)
quality arrowheads $30
-- item 2 = obsidian arrowheads (damage +50%)
herbs $50 - increase quickdraw duration by 25%
-- item 2 = powerful medicine, increase quickdraw duration by 50%

Note that you can EASILY buy every single thing if you do the extra missions, so don't stress about buying everything immediately. Just buy what you need the most and get the other things as you go.

The things you buy show up in your saddlebag. It only shows the "best" of an item in a given slot. If you buy a basic speed loader and then an advanced one, the advanced one takes over the spot the basic one was in.

Gun Walkthrough