I built my 6 tub rack with thermostat, heat tape wood and sealer for about $150. You can find damaged wood at lowes or depot and they will mark it down. Just takes some working to figure out how to make your cuts around the damaged area.
I also had a half sheet of wood left that I just built a 14 tub hatchling rack out of. Still have heat tape left and can wire to same thermostat as the adult rack. So really I built 2 racks for $150
I can pist pics if you would like to see them. Can also give you the measurements.