They are not a publisher in the strictest sense, just a *printer*. They don't do any promotion of the work nor do they do distribution. Those cost WAY more money than the physical printing itself, but it is those things that make pieces sell. Unfortunately, only the largest publishing houses these days can make significant sales because they have reputation or mountains of money to fall back on.
The first red flag is this: If *you* have to pay to get something printed, run the other direction, fast.