Depends on a lot of variables.
You could actually find out the assessed price, as their are 2 gov't websites for taxation purposes, at least where I am (Udon Thani) and quite accurate. One for land pricing, and other for structures. And no I don't have, wife does, and all in Thai.
Now weigh that against what you paid, hopefully not too much, and what you want to sell for.
I've oversaw 2 builds, and expected and got 10 % ROI per year on the first build, sold, and expect the same on the second build, under contract to sell now. Lived 7 years in first house and 5 years in this house, so a decent ROI, and have lived rent free for 12+ years of the 16 that I've been here.
As anywhere, should be easy to price, taking those not being motivated sellers in your development, and taking the average price, 2nd market, not buy in price, per sq meter and land size of land/property already sold, giving a good estimate of your market price for your development.
Hopefully you bought wisely, and will get a nice ROI. At worse, break even and lived rent free.
"Travel is fatal to prejudice, bigotry, and narrow-mindedness"..Mark Twain