You should be able to get a respectable, general purpose bike for $500 to $1000. Not a Chinese Amazon special.
Having said that, at my local bike shop, I've seen pricing go as high as $7k to $8k for a bike (this is middle market Thailand...for the high end $10k+ bikes, you'd have to go to Bangkok, where the super-wealthy Thais live or Phuket, where the super-wealthy Russian oligarchs live)
I have two Treks and they are great bikes.
first rate.
And always a good deal.