What Mark said - often builders from one area dont go to another area - the driving time is often not worth the hassle for them. I'm also guessing that good builders have sufficient business in their own areas.
+1 on the above. I tried lots of PBs before I found one that built inside the loop. However, it seems you are looking at a vinyl pool so that might be different. I don't recall any Houston vinyl pool build threads.
Oops I misread. You are looking at a fiberglass pool, right?