Bravo! Nice token!
The determining factors for a token's value are just the same as for a used car, collector coin, pair of dirty socks, etc. Supply and demand. Period. Tokens have little or no intrinsic value, so they are valued as collector's items only. Of course some modern tokens are still in use - you can buy a carwash or play a video game with some you find, but in the case of this one, the merchant who said he would give you $2 in trade for the token is long gone, so now it is up to collectors to value it.
So, just like with anything else, if you want to put a pricetag on your token, it needs to either be appraised (which would just give you a ballpark value since most people are not qualified to appraise trade tokens) or you need to sell it on one of the popular online auction sites which are regularly visited by numerous collectors of such pieces.
Even though I have collected trade tokens for 40+ years, I don't have any idea what this one is worth, mainly because I don't collect Iowa tokens and don't know the market for them. Every state and subtype of tokens (i.e. saloon tokens, general merchandise tokens, billiard tokens, etc.) has a different market. Some states and types may be popular (high demand) and some may not. I can tell you that this one is not listed in Ferguson's 1984 Iowa Trade Tokens book, but it is not the most recent one out for the state. That just tells me that the token is not common.
I will e-mail a couple of IA collectors to see what they say. One is working on a new IA book.
John in ID