You can easily spend that kind of money on a wood frame deck if you choose. I helped a friend build a 24x16 deck that also incorporates a wrap around porch and wide walkway down the 36' length of his garage. The whole thing has a full roof structure over it, built as an extension to the roof line of the house and the large main deck is elevated out over his walk-out basement. We used Timber-tech decking and a very nice extruded aluminum/PVC wrapped railing system. The timber tech decking alone was approaching 10 grand and the railing was well over a hundred dollars per foot, easily over 10 grand total. The framing and the weeks of labor is not even factored into those costs.
Material choices, size and site conditions is a major factor in what any project costs. It would take an enormous amount of detail for someone on the internet to determine if 52k were a good price for your project. I would recommend you get at least 3 quotes on the project from reputable contractors. If one is substantially different than the others then there is probably a reason.
That just seems like an extreme price for an above ground pool. We were quoted close to that same price for an enclosed inground pool. Our current AGP is 19,328 gallons is a top of the line resin pool and ran around $5000 installed. The Spa cost sounds reasonable. The deck cost at $39,750 just sounds extreme to me. You asked, but it is your money.
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.
$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)
$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.