What can you afford, that is the question. Just finished a pool (filled June 30th), we started planning and visiting with builders back in February. We had offers and different designs from $43K to $95K but we ended up with one that cost about $70. Be careful of "national builders" they tend to be pushy when they sell their designs and want you to come to their show rooms immediatley to start picking out tile, decking, coping, etc. After 3 visits with these types we started talking to independent builders who do more custom rather than cookie cutter pools. I ended up using a company that actually is officed in our community so I know he is solid (started in 1986) and is right around the corner if I ever actually need to track them down.
As far as unforseen expenses, yes there are always some of those...mine were, main electrical re-route through my back yard ($2000), gas meter upgrade (for spa heater)$350, irrigation system reroute make operational again $500, all the new plants and patio furniture your wife will want to buy when it is all done $4000+!!!
Words of experience (not wisdom), be patient!
I would be weary of folks that said they can build your pool in 4 weeks or less. As frustrating and as much as you want to have it ready, well built pools are not thrown together. They take time to be done right, ground needs to settle, rebar needs to be done correctly, plumbing done with right size pipe (with no or very few 90degree angles and no stacking of pipe in trenches...this is in case there is a problem later, you don't have to dig up the whole slew of lines to get to one).
Don't let them bunch up your pumps, filter and heater on a small pad, good start is minimum 3'x 10' pad, easier to work on and replace pieces later. As far as design goes, do what you like...a good graphic designer that works in house with a pool company will redo your pool as many times as you want till they get it the way you want it...if they tell you they will only do it 1 or 2 times, go find someone else!!
I can't tell you what it will cost going forward but besides a little more on my electricity bill, chlorine tabs and acid at $20/case I don't see it being very expensive once I get the water balanced and can start adding salt to keep pool balanced. I am assuming only about $600-$1000 annually.
One more thing, it took us 8 weeks exactly from first day of dig until filled pool, only 2 rain days, so that was the frustrating part but looking back thats less than 60 days to do something that we will enjoy for many years to come. If you want our pool builders name send me a PM and I will get you their name and number. Good luck!