You will be surprised how far EZ Drummer will take you. I have BFD, some other name brand I can't even remember right now, Superior Drummer 2, Superior Drummer 3 and EZ Drummer. We consistently wind up using EZ Drummer in the final mix. For the sound. What is also cool in SD3 you can load and play EZ Drummer inside of it. So I can mix kits if I need a different snare or bass drum but still be using EZD.
You can buy the MIDI packs in a 6-Pack. Hit up Sweetwater for 'best price' and load up 6 at a time.