There's a couple of places on the net where you can buy samples for your productions. Banginbeats.com for instance and a couple of other places I don't feel like sharing to the lot hehe BUT! It all depends on what kind of flavor you would want out of your beats. I've bought alot of samples but more than often I use the most shitty things I can find or sample and tweak them to suit my needs(if I want them grimey...). If you're serious about your production you might as well start now with learning how to layer "percs" to get that dope kick and crispy snare. Even if you buy your perc samples you might feel the need eventually, to layer them. To put it simple; If you want the grimey & heavy kind of beats, why buy perfect samples and then degrade them to suit your track...? Isn't it just better (and cheaper) to sample them from something that might suit you?
-Nito