I do believe that a 40Breeder can be drilled. I have one that has a pair of bulkheads in the bottom of it. I am not 100% sure about the side glass, though. I just checked mine with polarized sunglasses and it does not appear to be tempered.
I paid $270 for mine because I got it when I was on a group buy on BulkReefSupply. That is one of the best prices that I found. If you order from them, you should also get 2" and 1 1/2" true union ball valves from them while you're at it.