i didn't even know marine rays were on the market.
There are freshwater species that can be housed in home aquariums. Minimal size for a growout tank is 75 gallons, minimal 120 for full adult size. They need extra wide walls and if you can get a shallow tank, the better. Longer and more wide is the issue rather than tall.
One day, I plan on keeping a single freshwater ray. I'd like a 260 gallon tank, but most likely I'll have to make do with a 140. (I plan on buying a double-wide mobile home in the near future, and I'm not sure if those floors can handle 2,800 pounds of pressure).
I don't know anything about marine rays, but there's an excellent book about the care of freshwater rays called "freshwater singrays" by richard ross.
I've been researching these guys ever since I journeyed back into the fish hobby last August, and only now do I think I'd be ready to care for them. Unfortunately, my appartment is too small, and I have enough tanks as it is.
Anyway, read up on everything before you make a move, and use good judgment.