Well I finally got it all laid out for the upgrade. I got most of the money, I'll get a dechlorinator soon since it really would be a headache to buy spring water to fill a 55 gallon tank

, and I'll get the aquarium stand soon after the tank purchase. It all amounts to more than $350

! Who said turtle care was cheap. I put them in a 12 gallon bin to clean the tank because we're going to sell it. So I think the thing is pretty solved here, though I doubt shrinking the tank size to a 12 gallon bin.
I think I'll post pics of the new habitat when it's ready.