According to my inventory, I have 119 Steamworks Trinkets. However, when I try to go buy items I get an error saying I don't have enough trinkets.

Not sure where the issue is originating from, but the items I am trying to buy are: Gold Leather Gear Choker - 10 Brass Ray Gun - 25 Brass Steam-Wing Kit - 30 Elegant Brass Pocket Watch - 45

You have to turn them in at the shop. c:

Ohh! thank you ^^

No problem!