I financed my first system in 1973. I had forgotten that until I read Ozfly's confession. Ever since then, I have provided myself with upgrades by trading audio equipment. In fact, after thirty-odd years of swapping, I'm very sure that I have no money at all in my system and might actually have profited. Who knows?
Certainly, when the years of use and enjoyment are factored in, I can say I have profited enormously.
This would seem to indicate that I am philosophically opposed to borrowing to buy audio gear, but after reading some of the arguments here, I can see where it makes sense for some. After all, if you buy new, depreciation on this stuff badly eclipses any reasonable interest rate. However, if you are paying a credit card company 23.99%, refer to the first post by Narrod.