Damn!!! Tell me where you live so I can get either rifle at those prices! I haven't seen a Bushy under $1k for over 2 years, or a DPMS for under $1100 for just as long.
DO NOT under any circumstances take what they offer you at a gun store. It'll probably be around 60% of the value of the rifle. It's a good starting point, but with a rifle almost 50 years old, they will undoubtedly tell you there's lots of things wrong with it and they will "graciously" take it off your hands for a measley sum. Post a pic or 5 of the rifle, there's lots of knowledgeable folks here, they can get you a good estimate.
Between Bushy's and DPMS, both are good rifles. I own two Bushy's and have shot 3-4 DPMS's that friends have owned. I don't know if it's telling or not, but I still have my Bushy's, and they've all sold theirs. Again, I'm not sure if that's telling or not, but I've had narry a problem with mine.