How about buying the one that fits your pocket book right now.
Play with it for a while. Decide if it's adequate for what you're wanting to do. All the while saving some more coins.
If you decide it isn't going to work for you, sell it and apply the selling price along with what you've (hopefully) saved up and go to the next step.
Keep doing that until you are happy with the performance.
Knew a girl who did this with cars. She wanted a new Mercedes so bad she could taste it. But on a college student's income it just wasn't practical so she bought a much older MB, did some work on it while saving up and progressed to a newer MB after selling the first one. Did that 3 or 4 times and bought a REALLY nice, brand new Mercedes when she graduated.
Just a thought.
