I'm looking for places to trade a few BTC securities, but the only one I have found is MPEX. It doesn't seem very user friendly, and 30BTC is kinda prohibitive for someone who just wants to test it out.
Thanks.
Have a look at the "Securities" sub-forum, under "Marketplace".
Check out btct.co, bitfunder.com, cryptostocks, and ltc-global (uses litecoin instead of bitcoin, but the idea is simmilar).
You will also see references to glbse.com, but that exchange closed down suddenly a few months ago, the drama is still ongoing.