Looking at prices online, most miners are ridiculously overpriced - people are selling miners which operate at a daily loss (I suspect to people who can't math well and don't understand mining). Old block erupters, for example, sell at $50 a piece and earn less than $1 per year. It's nuts.

Decent deals I've found are old S1s for around $100, things like that. A realistic price I've found that tends to balance this crazy demand with a decent roi is a machine that ends up costing about $1 per 2/GH/sec. ie, a $100 GH machine is about $50.

Maybe you could price it something like that?