You're making the choice to spend that money with those options. The cost of the spa itself could well be $10K and I know our breakdown of AGP with gas heater and no landscaping was as follows:
Equipment/Pool - $11,000 for a 12x20 oval with 260,000 btu gas heater sand filter, 1.5hp pump, salt system, locking stairs- included pool site prep, install, plumbing the skimmer etc, to the filter/etc.
$600 water
$100 of patio stones for equipment/ladder
$2500 for new electrical panel, all wiring, cable from house to pool equipment
$1500 for gas installer to run gas line to heater, enlarge gas line in house to 1.5" pipe (to allow for furnace, water heater, dryer, and pool heater all to be gas)
Incidentals-
$1300 to remove sunroom/make space for pool
$1800 for concrete removal and foundation crack from sunroom's footings not being deep enough below frost line
This is all on a FLAT yard with a small pool and no deck/spa. That said if I'd had that $ to spend I could have had an inground installed here. Maybe smaller- and I don't have a huge decking need. The larger area we had to install a bigger pool was very sloped and a semi-buried was coming up to about $25K, 30$ K with NO landscaping/fencing etc. Slopes really increase costs, but think of it this way - you don't want your pool water to rocket down the side of a hill.
Putting in an iron fence earlier last year also tripled our fencing costs.