I am thinking of purchasing a macbook pro. I have been looking a new and used models. I need a heavy set of ram for music performance. When you purchase a macbook pro in the apple.com store, it is an astonishing $1,000 to upgrade the ram from 4gb to 8. Why is this so expensive? I was looking on ebay and other sites for a possible cheaper priced upgrade that I could install on my own. My question is: does the ram that apple installs in their computers perform better than, say some generic 4gb ram I purchased on ebay for $50? Could I upgrade to 6gb ram rather than 8? What is my best option?