I don't think there is LC peanut butter, per se, but you should look for all natural peanut butter, which only contains peanuts and perhaps salt. The regular brands contain sugar and transfatty acids and more junk.

I personally buy macadamia nut butter because it's 1 carb/ 2tablespoons. It's $5 for 8 or 16 oz, depending on the brand. When I find the 16 oz, I buy a bunch. Whole Foods sells it; not sure who else. For the natural PB, I've seen it at the regular chain grocery stores like Kroger and Meijer's.