What are the current best solutions for the 30 YC 'ideas'?
hga: 10. Auctions: http://gunbroker.com/, which was started immediately after eBay wimped out on auctions having anything to do with firearms.  I've bought stuff on both and sold stuff on GunBroker.com and the latter is much better and has several ideas worth using on most any online auction site.One thing that might  be hard to replicate: firearms, ammo, etc. are serious things, e.g. you can't transfer a firearm across state lines without going through a licensed dealer and getting a background check.  In the cultural sense reputation on GunBroker.com is treated very seriously; I'm not sure how this could be replicated in other areas, including ones where prices of items are lower.