I have some of those cheaper amps from Amzon. They work ok or better than they should at the asking price. Disposable equipment at disposable prices. No, the stated power ratings are typically bogus, but so are a lot of other brands (or superfluous, at least) claims beyond what is actually audible. Powerful enough for 4 ceiling speakers depends on other factors but for two that can otherwise get by on 20 or 30 watts, it would likely be fine. If not, put it on a desktop system and get something better if it fails to impress.
I recently got the Fosi Audio BT30D Pro and while it's no audiophile piece, it's good enough for me on most days with casual listening. But then I don't really qualify as an audiophile and am somewhat easily pleased, or at least realistic with regard to the music quality I tend to choose. The one thing about the cheap amp is it is dead silent. No hiss, pops or humming at all. I bought it as a travel amp to take with me when I visit friends/relatives or for going out of town. When I'm away from my home system, this one certainly suffices.
If you're serious about music, build an all-out system to scratch that itch, but not everything we listen to has to be so involved. In other words, we can have multiple systems and they all don't have to be winners. I have 7 different systems from vintage to current that accomplish different things at different prices. Some of the budget stuff is pleasing to listen to in it's own right.
Not to disagree with the others about buying used, there are some risks there as well but it's not a bad way to go, more often than not. I buy used as well and it has served me well mostly, but then, I only buy because I can usually repair or rebuild it if worst case happens and still come out ahead.