It should be noted that if they don't themselves design any of the modules that would require certification, but instead just use already certified third party modules, that greatly reduces the amount of testing their product needs.
I've read that can get the cost of FCC certification down $1-2k and the certification time us under 5 days.
If you design your own module, then it is $7-20k, and will take 4-6 weeks. (Once you've certified that, though, then if you reuse that same module in other products it is like using a third party certified module, so $1-2k for each subsequent product).
Generally speaking testing labs will run a series of common tests that satisfy the various regulatory agencies. In other words, you don't have to run four separate sets of tests to obtain UL, FCC, CE and TUV. I've done this dozens of times over the years.