I am new to the AR knowledge.  I would like to convert my Upper to an A3 variant.  So Ive decided I should get rid of my current upper.
What is a reasonable price to ask for a DPMS LO PRO Classic upper complete.  250 Rnds through it.  Great condition.  
What other brand uppers are compatible with DPMS Lower's.  My main concern with the Lo Pro upper is the lack of standard sights, and a  forward assist,  although I have a few friends with many more rnds fired then mine and they have never needed this feature.  I am a bit of a traditionalist.  Any advice would be great.
Thanks

Well, I can't speak with complete authority, but  you can buy the Lo Pros around here new for somewhere in the neighborhood of $650, so you have to figure the lower is worth around $225 or so, and that leaves the upper at around $400 or so...shaving off a couple of bucks 'cos it's used.  

Don't worry about the lack of forward assist, or no ejection port cover...most people here know that model anyway.

You can add or subtract a couple of bucks either way, depending on where you live, and what that rifle goes for.  

Now, if I'm not mistaken, the Lo Pro is a flat top...so is an A3.  Are you trading/selling this because you want the A2 (built in handle/sight)?  Personnaly, I'd stick with the Lo Pro...much more flexibility with sights/scopes.  I've got 4 ARs, and they're ALL flat tops...but that's just me...I prefer to stress about what sight or scope to put on 'em [:D].  

The only thing I've ever accomplished with the forward assist is to make a stuck round REALLY stuck!  Had some old PMP brass I reloaded...it jammed real bad...when the bolt didn't close all the way, I gave the forward assist a shot without thinking...I had to get a HUGE screwdriver and pry the bolt back from the mag well.  I know it wouldn't have been anywhere near that bad had I not hit that forward assist.  

Check the Equipment Exchange, and see what similar stuff is selling for.  I have a RRA 16" varmint upper I'm selling for $375...so $400 for yours is about right.  I could get more for mine *maybe*, but I'm looking to do another build, and want some fast cash.  

Good luck!