Step back and see if they're still in business a year from now.

And if their writers are actually making money.

What puts me off is that they are not paying advances at this time. Maybe that's normal for e-books, but I'd rather get paid for all my hard work.

In the meantime, submit to bigger publishers with a longer track record.

Publishing is weird--you start at the top and work your way down. Find the biggest house or agent on the block and submit to them first, then work your way down.