Yes, no question a new bike is the wiser choice. If you need to hang onto the bike a while longer then go ahead and get the crankset, but not if you are planning to sell it soon, as you won't get much extra by doing that. As for where to find a crankset, how about you Google 48-38-28 crankset - lots of choices starting at $29.95. As that combo is not as typical on the more modern BB's you will tend to find that they will almost all be square taper.