My LQS does a sampler BOM for which I have tremendous respect. The cost is very reasonable - usually about $20 to sign up and free fabrics for following months if you show up with the completed block from the month prior. In theory you can get your 12 blocks for your initial $20 investment. Additional charges for 'finishing kits' comprised of sashing; border; backing fabrics but that is up to you.
I've come to the conclusion that I'm not a fan of sampler quilts for myself but I think the BOM program is a fantastic skill-building exercise. I'm in the process of finishing up a couple from a few years ago now just to get them out the door.
If anyone is looking for skill building, I second the suggestion of quilterscache.com. Great site with tons of resources.