Originally Posted by linberl

Buy the best frame you can afford. What you will replace are the components (derailleurs, cranks, cogset, chainrings, brakes and levers, shifter, etc.). Keep in mind that, should you sell later, you will not get back what you put in financially, but otoh you will have been riding a bike you "created" and enjoyed. I did that with one of my bikes...replaced components piecemeal as I had the $ and found the right deals. Any bike that takes standard components can be upgraded, you'll just have to find the appropriate size compatible parts. Since you said you aren't a mechanic, I would look for a community based bike workshop near you. They will help you decide what to upgrade and teach you to do the work yourself - if you upgrade by paying a LBS for labor the cost will not be remotely affordable. In that case, you're better off saving and buying the bike you want from the start.