As mentioned before, there is an issue of trust of the poster. I'd hate to fork up some bits only to see an ascii of a penis. The last thing you need are people ruining the concept from the beginning. To fix this I'd recommend the following:

Enable an account login requirement. Each account should have a profile page automatically generated for them with a summary of all bins. Each bin should have an upvote/downvote option for those that purchase to rate the item. The overall rating of the user should be visible on their profile page just like other services like eBay that call into question the trust of the poster. This is the only way to give users a chance because offsite vetting is just too nocuous. This means users will have to slowly build up their reputation before trying to sell high priced bins. Some people are already posting for 0.1 BTC which is rediculous imo, a first post should be a building block, something like 1000 satoshi for example, at most... maybe.

I think this has great potential and something you can monetize down the line once it becomes popular. But users need a reputation system. I daresay that if you don't, then someone else will because with a rep system, this could be real good.

BTW, I did notice an issue with one of the bins, the content was showing as "bought" even though I did not buy it (it was just an ascii of a penis).