Sonic Realty gold series is a value for the money, I wouldn't even buy any one seperate as if you just save your dough you can have all for 400. Next I would look it is Reason Banks as far as synth sounds. They do some great stuff, they have the proton Refill and the orange microwave Refills. Check them out and see for your self. They are geared more towards techno, but for the price you can't be the quality and value of the sounds. Next hit up the akai format CD's and get reload like it was mentioned above. You can get those CD's for like 30 bucks these days and convert them to Refills. I'm honesty more of a sampler, but I love to have a bunch of sounds avail, you just never know when you need them.