Might be worth asking other sites what they do. I know some here read and/or post at pistonheads.com.
The guy that owns and runs that (petrolted) does a damned good job and sells merchandise which arrives on a next day delivery basis. My suspicion is that he has had to shell out money first to buy the stock though.
Maybe you should either ask regulars here to put up a small; amount of capital to buy the initial stock, or get some ideas of pricing then ask the regulars to order what they want.
The profits could be used them to order stock in. Not sure whether the stickers made a profit, but something along that sort of line would seem ideal.
Might be better to order items gradually. After all if you suddenly announce you have T-shirts, Polo Shirts, Sweatshirts, Fleeces, Flags, mugs in stock I am unlikely to order one of everything. If however you say you say you have fleeces this month I will probably buy one. If Polo Shirts come in next month I am likely to buy one etc.