This is actually your best bet. Just start cheap, it will work. It will either meet your minimum threshold for awesome, or it won't. If it does, buy moar music. If it doesn't, buy something else. Do your research though -- more expensive does not necessarily mean moar better. And after you do research, do not resign yourself to other peoples' opinions -- decide for yourself if particular tube sets are better or worse. If you can front the money, the best thing to do is to buy what tubes you can afford, and keep the ones you like, sell the rest (as "lightly used", of course).
Hello, my name is Peter, and I'm a tube-oholic.