I usually have a good idea of the value before I start the purchase process. I'm happy if I can "ballpark" the price. Something specific, I'll have looked over auctions from ebay and checked the prices on a few online shops that I trust. CoinValues and such only come into play as very rough guides. On IHCs for example, I'm willing to pay about 30% more than the average ebay price if the coin is really outstanding. BUT that usually puts me at about 85%-90% of CoinValues. I usually just tell the dealer that I'm a buyer not a browser and that I'd like the best price right up front. If the price is too high I just say "Sorry" and that's the end of it.