Try really hard to get him on Massivore, starvation method isn't fun but it's the most effective method. If you really feel you have to, give him some feeders once to fatten him up and get on those pellets. He's most likely stressed from transport and shipping to a supplier then store if he's really straight from Thailand at that size. It'll take a little while for him to adjust to captivity but as long as you do all of the above he should be fine. Also I'd say you didn't overpay as long as there aren't any further issues health-wise and you enjoy and love your new (and good sized) NTT.
