Join Date: Jul 2011
Location: Fayetteville, PA
Being a custom furniture maker myself, it all comes down to what lumber and how fancy you want it.
I can tell you a solid oak (no plywood) would run about $300, but again that is solid oak. Now you take it to veneered plywood and faceplate it and make the doors out of solid oak you are looking at $100. This is just for custom built DIY - if I were to build it for someone:
Solid Oak: $1000
The concept of a stand is quite simple really. You need to look at how much you need to support. 75 gallon aquarium filled with water weighs 600lbs, then to be on the safe side say 400 lbs for gravel, soil, and possibly a canopy. This may seem excessive - but always good to over build is what I say.
So you are looking at supporting 1000 lbs. It may seem like a lot, but you'd be surprised how much lumber can support (length wise, not flat). I would say 5 sides would be plenty, 3/4" thick. This would make for your cabinets. Then a piece on top and bottom and voila. Now, if you want to plan for any possibility here is what I recommend and what I have planned out for my 100 gallon.
Build a 2x4 frame, all long pieces sitting on support pieces, never support pieces holding long pieces. Build 4 walls for supports, then veneer, build doors, voila. It'll hold a heck of a lot more weight than you can throw at it.
In the end, for a stand, unless you can find a great deal: DIY! Don't buy particle board crap or pay outrageous amounts for nice stuff. Now - I can understand if you don't have the ability (tools, space, etc) to build your own - in which case having one built is going to be your best bet or finding a used one.