Sorry - this one slipped past me...
It's easy to DIY. I put a 512GB Crucial m4 into my 15" late 2011 MacBook Pro last April. There are hundreds of videos on YouTube on how to install the drive.
First, decide on which drive you want - there's a good info and buyer's guide here. Although much of the discussion is about drives for Windows machines, most buying advice is good for Mac's, too. You'll also want to get yourself a toolkit and an external enclosure for your old drive - I got both from OWC.
After you have the drive installed, follow the directions here to format the SSD and clone the 'old' drive to your new SSD.
Any questions? Yell back...
Clinton