Absolutely not a deal killer. Again, he's just trying to make more money from you (and you're correct in recognizing that he should have brought it up before now). Just buy some racquetball balls and cut them in half. When you can afford them, go back and buy some brass cones, and decide which you like better -- it's that whole coupling vs. decoupling argument all over again. If you have something ultra-solid, you want to couple to that, otherwise you want to decouple (oversimplified, and IMHO). Decoupling will almost always help (unless you happen to already have had a very nicely coupled setup), hence why I recommend the racquetball balls.