Great that electrical and HP are taken care of! For the mix you are considering, make sure you have at least 600A 3 phase power and 15 tons of HVAC. Best guestimate given the mix you are suggesting.
Hard to do the layout without your bed mix - room sizes might vary. Try to get as much equipment and services in there as you can!
Demographics are "great" - I never know exactly what that means, but hopefully it means you have tanners! Be aware, sometimes your most likely users of tanning are NOT the highest income folks. They tend to be more "educated" and have succumbed to the dermatologist claims that tanning is bad. Also, they don't need to tan to "look" like they went on vacation - they can actually go on vacation!
I'd do at LEAST two HP - one 360, one stand up. Make sure you have a room wired to do a 3rd down the road - laydown. Sell them BOTH as HP -- not "oh, and we have a standup". Have them alternate between one and the other.
If your ethnic skin tones are darker (e.g. hispanic, asian, greek, italian,...), consider a HP/LP mix bed (like the Sportarredo Extasy, Soltron Chill,...). Only if you have a lot of these skin types.
Big VHR - I'd have at least two, plus a 3rd with a GREAT VHR Standup. Suncapsule or maybe the KBL Pure Energy on the standup, big VHR could be
UWE S-class or Cayenne, high end Ergo or Soltron, KBL 6800 or 7900, etc
Small VHR or VHR/HO mix - Soltron Hot Peppers, Ergo 400, Future Elixir, Ambition 300, etc. 2 of these. Could put the standup at this level rather than at Big VHR level - depends which one you chose and how it tans
1 base bed - for specials, loss leaders, get them in the door? Not sure if I would add this one or not - an argument to be made either way
1 VersaSpa and 1 "Services" room to do custom spray, teeth whitening, body wraps or any other services down the road you might bring in to add $$ revenue.
For best "deals", look for nearly new (e.g. used). Plenty of very nice stuff available if you can move on it quickly. For example, see my post in Trading Post. We have Matrix HP,
UWE Cayennes with less than 100 hours, an S-Class, a Soltron Chill and a Versa Spa just installed in December,.... The failure of someone else can be your advantage to NOT failing by starting out with a substantially smaller equipment cost outlay.
Also, there is a guy on another board selling his walls - he is .25 miles up the street from my salon (closing after a year). Very nice walls, great price. That can be a way to save and then just buy the parts/sections you need to adapt to your layout. But 24K on Eurowalls is pretty standard pricing.
My number is below - call or PM if you want to discuss further!