Nikon Z6 mirrorless setup - I should mention some of the items are part of a demo setup from a pro friend, but will list retail prices too... to compare the difference with a compact. I've outgrown the compact after about year 2.5 underwater.
I'm prioritising a wide angle setup first.
Nikon Z6 Full Frame Mirrorless setup:
Nikon Z6 body: $2300 new, $1500 second hand
Housing: $4400 new, $1900 demo model
Nikkor 8-15mm fisheye lens: $1300 new
8" Dome port: $1450 new, $1000 demo model
Lens converter & port zoom ring: $175
Port extension ring: $250 new
Ball joints for tray x 2: $50 each new
Vacuum system: $330 new, $180 demo
2 x strobes - indecisive on brand yet (tossing up between Retra and INON), expected new cost $1,300 each or ~ $650 each second hand
I will reuse my video light from my previous setup
Total cost of setup new with two strobes - which is only for wide angle: $12,905
Total cost of combined second hand with a few new items: $7,705
To be clear, in order to shoot pictures I need all of the above except for 2 strobes, potentially I can go with no strobes to start or one strobe. Then in order to shoot macro, I need to add on the following items, which will be purchased new:
Nikkor MC 50mm lens: $1000
Port: $400
Extension ring: $250 (TBC)
Additional $1650
I can also then use my existing wet lenses on TOP of this 50mm lens, so I can use the SMC+15 diopter for additional macro capability. Some things that you buy for the compact setup are reuseable with a bigger setup.
Anyway.. hope this helps. I'm very keen to get my mirrorless setup but still heading out to the reef this weekend with the Sony
I'm sure others will have different advice on which way to go, but personally I've appreciated learning my craft on the smaller more portable rig (especially for tricky entries and shore diving, and I'll keep the sony for shore diving here), and now am looking forward to the challenge of porting those skills over to a mirrorless rig. I've also been doing a lot of landscape/topside shooting with DSLRs lately and really honing those skills, too.