USA DB7 Vantage Market Values

I'm on the East coast & in the market to purchase a DB7 Vantage. I've been watching listings vs. activity on 4 or 5 websites here for the past 6 months. My sense is the coupes (convertibles are in worst shape) are well under $50k, regardless of asking prices. Last week I made an offer on an '01 with 20k mi in very good condition to an East coast dealer for $42k. Asking price was $50k & it was turned down. Yet, dealer could not provide any comp sales, though I could. We all want our cars to be worth the max, but really, was my offer that far off?