I built this rack out of 3/4 melamine for the shelves, 1x 4 for the sides and one in the back.  1 x 1 for the runners on the shelves and one as a stop in the back.  I had home depot cut the shelves for me.  They spit a 49 x 97 into 24.5 x 19.  I was able to get ten pieces out of one sheet.  I bought 5, 1 x1 and 5, 1x4's.  The left over pieces of the 1 x 4s went onto the top and bottom to make it more rigid.  Got the casters at wal mart.  Took 18 ft of 4 inch flexwatt and hooked it up to a ranco.  Which I got from Reptile basics.  All together the rack was 150 with the tubs and lumber and screws.  The heat tape and thermostat was about 140.  I didn't think it was a bad little rack for under 300 bucks all set up!  If anyone is interested in how I built it let me know and I can give you instructions.  Although it is pretty easy if you have some tools.  It took me about two hours to build it and probably another hour to put the heat tape in and tape it all down.