Please bear in mind prices are not bitcoin fractional's that is it's not 1 for 1bitcoin but 100000000, all prices currently use 64bit integers, so the number 1, is actually 0.00000001 of a bitcoin(I think, it's thereabouts anyway).
We will continue working on the client to improve it's usability.
Please also keep in mind that this system is still under active development. That no orders sent to the server are encrypted (although they are signed), and that the systems security (both the programming of the system, and the actual machine setup) needs considerable work and testing(moreso testing really).
Long story short, use this system now at your own risk(for playing around it's not a problem but actually listing companies for more than small amounts of bitcoin is a little risky).
Please note that if there are any issue's I will do everything in my power to resolve them and attempt to keep this running as smoothly as possible.