First off, what are you looking to spend? Secondly, the guy is telling you the truth. He is either really honest, or really stupid. ANyway, once the new model M3 and M5 are out and being bought like candy, the price on the E46 M3 will most definitely drop considerably so the dealer can get them off his lot to make room for more of the new models. This is about the time when nobody will be on Bimmerwerkz. We'll all be financing 2005 M3s for what used to be the price of a 330.
Hee hee hee... But seriously, waiting a few months, and doing some researching, can save you a lot of money. Hell, either save up a bit more of a downpayment, or save up some cash to get some aftermarket stuff as soon as you drive that beauty out of the dealership in a few months. It will definitely be worth the wait. And deal with the same salesman as before. He sounds like he won't rip you off.