MSRP is the only static # you have so I don't agree that it's useless. IMO, what is useless is all the other BS dealers talk about with volume discounts, invoice price, incentives, hold backs, blah, blah, blah. Give me the bottom line and don't tell me when I come in next week you won't still sell me the truck for that price.
Anyone ever notice every couple years there some new term we all start talking about regarding price? That's the dealers way of constantly moving the target. Dealers are in a tough spot these days with all the sharing of information (the internet). They are always trying to stay a step ahead.
To answer the OP, paying somewhere in the ballpark of 80% of the MSRP is good. Some can do better if it's an expiring model year or the dealer is really hungry. Sometimes you do worse. There is also some regional influence.