I'm new to selling on eBay and am surprised at how well we're doing so soon... honestly, there are tons of ideas, tips and the community support board over there is a big help if you get in a jam (non-payer, what to do if..., etc.)
Stickers, decals and stuff IMHO would do well - low shipping cost, impulse buy - people love stickers... my mom bought a shitload of those Dale Earnhardt ones after he died in that crash thinking that they would sell out - at $1 a pop I'm sure that guy made a wad of cash, just on that one sticker.
And I agree on the trial and error... it's like site building - nobody can tell you what's gonna work for you or give you a blueprint... check out the rules/guidelines and how-tos on eBay.com and then make it your own....
Good luck to your friend!
