They have a tier list of prices, the first tooth should be way less than 10,000 Baht and every following tooth should be less than a 1000 Baht but definitely less than implants. That should includes everything with metal frames, excluding extraction of teeth.
since you own an apartment in BKK, I assume that you have got a different visa than a tourist visa. In that case, most probably the IO would not ask you to show cash.