I decided to purchase a new laptop from Apple and went for the new model, which is a non-retina display Mac Book Pro. It came with 4 gigs of memory and I decided to add 16 gigs of memory for overkill. I use Adobe Photoshop CS6 and Lightroom 4 frequently and these are memory hungry applications. The improvement is very noticeable.
Surprisingly, these new Mac Book Pro unibody models (non-retina) are pretty simple to upgrade. Just remove the back cover and the memory banks are right there! It took just about 10 to 15 minutes.
Don't buy memory from Apple. You can get it cheaper else where. I got mine from OWC. Having the right tools for the job, and here is where the Pro Tech repair kit from Ifixit came in handy, is a must. This tool kit comes with everything you need to tackle a repair job.