Hi bodaciousbonsai, even if I had the time to build one for you I do not think you would like to pay the shipment from Sweden!
About cost it is quite expensive, the market in Sweden is very small for acrylic and Sweden is a small country so the price is high. I would say that only the cabinet costed me about 600 US dollar in material and I do not dare to count hours.....
For the framing of the interior I used Teak for about 200 US dollar and I bought 2 sq. meter of epiweb. I could by less expensive wood but I like teak for it durability under wet condition. I have not seen mold on teak..... About light you have to find something in the US, I think the price is difficult to compare.
For cooling IF i decide to go the hole way I think I will by a small refrigerator and some ventilationtubing and circulating air between the refridgerator and the cabinet. To build in a cooling element into a finished cabinet I would not dare, I have seen it but the solution to circulate air seems mych easier. The "inventor" of epiweb builds orchidarium with cooling with air circulation, they look like this:
and can be bought at
Dusk Tropic in Sweden