There are threads on every writers forum, including this one, about publishers to avoid. Do look for them. And one basic rule: the money only flows one way, from the publisher to the author. If you are asked for ANY money, for production, editing or anything else - that is not a bona fide publisher. In one way or another, it's a vanity press, and you are wasting your time and your money. No vanity press deals with the mainstream book trade, your books will simply sit in the warehouse. They make their money from the authors and their friends and family, who are usually the only people to buy copies, at inflated prices. Do not approach them.
If you decide to self-publish, then obviously you'll be spending your own money, that is different. I think the people you are referring to are PublishAmerica - as I said, you'll find specific threads on this forum, and others, about them. Here you go:
How good is PublishAmerica?