Hi,
Last year we had an inground swimming pool put in- 16X32. There were tons of extras that you could get to add on a lot of money- but we just wanted a basic 16 X32. We did have stairs put in the shallow end as an "extra" and a slide. Other than that- no real extras. Ours was about $27,000. The gas pool heater was on top of that- my husband is in that business so he ran his own gas line and bought the heater. We love our pool- but if you are considering it, I would difinitely pay the extra for a heater. Then you can enjoy the pool for more weeks! We opened ours in early May- and last year we had a family gathering in October on Thanksgiving and the kids were in the pool. We closed it after Thanksgiving. The heater helps for summers like last summer where it was not so hot.
But, we had quotes from $25,000 right up to $60,000 depending on if you want a concrete pool or fiberglass- then there are salt water pools and zillions of real options....I guess it really just depends on what you want.
By the way, the other poster was correct about checking your insurance rates. Our monthly home insurance rates more than doubled and we were informed that had we put in a diving board the rates would have been even higher!