Oh, there's no doubt it's a great deal. I'd only buy the pair if I thought one might be sufficient (check benchmarks; for your games it may well be) allowing you to sell the other. Possible problems with multiple GPUs, especially the microstuttering issue that was recently described in http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html
make me reluctant to recommend a pair of GPUs, when a single strong card will have none of those issues. There is also the question of power.