good friend of mine ran an ebay business, basically bought rare heavy-metal and goth CD's by the hundred - i guess that's easy to do with all the independent labels out there - and sold them for a decent price.
most of the rare and strange stuff is not in a&b etc., so there is a huge market out there.
he got a good reputation on ebay and sold all over the world, but eventually tired of ebay's cut and opened his own url:
http://www.heavymetalmusiccd.com
sells rare music and some movies, posters, etc. also box sets that are super-rare, like 100 or so made, he is high on some of those lists for promotions and non-published stuff.
what's real interesting is how small of a world that genre is, and how many musicians he has gotten to personally know. guess it pays to mix business and pleasure.