I can build you a nice custom acrylic frag tank if you are interested and not in a terrible hurry(not as cheap as a glass tank though).I got a few projects going now I need to complete but after that I can do a frag tank.
acrylic is lighter,easier to drill and gives you the ability to go shallower then a factory glass tank.It scratches easier so both have there pluses and minuses IMO
Option two would be grab one at TFP on the day of the swap as they are usually 30 percent or more off retail.Combine this with any coupons or other perks and you can have a new aquarium for cheap.You will need to drill it or whatever to make it like you want it but this would be much less then a acrylic frag tank.If money is not the issue,I would go for acrylic.There are some very nice designs out there now and you can buy one on ebay if you are not looking for custom dimensions.I will say that acrylic is now expensive as it is driven by the price of oil given this is a major component in manufacturing.