Plugging these patio11 posts because a)they might be helpful if OP hasn't read them and b)even if OP has, somebody else here might not and they're pretty much evergreen:
Just to echo Patrick's default pricing model. If it's too cheap (and you currently are), I would not trust the developer having resources to make the product stable enough for me to trust it with my data. Also, it costs money to go through certification (without which you will not penetrate the market where this pain point is clearest).