Two things;
If it sounds too good to be true it probably isn't
and
You get what you pay for.
With that being said, I bought a "JBL" Bluetooth speaker off of Lazada for 400 baht and not the usual 4-5+ thousand baht, the sound was "OK", but the battery life was crap, it wouldn't last a hour. Nowadays, I keep it outside in the garden and keep it plugged in and play music when I'm washing my dogs or some other minimal garden patio activity.
When it's family BBQ time or I have friends over I bring out the "real" speakers.