not usually at big stores like Cabelas/bass pro/ academy because they will get their sales..even without yours.
Mom and pop stores will usualy come off price a little bit but Ive never had them take off more than $10-$15.
Keep an eye out for manufacturer coupons as mentioned above. They will run mail in rebate sales from time to time or promational packages. You can get the XD "essentials" package that comes with the gun and 2 mags for $400. if its not in the essentials package its around $450.
Budsgunshop.com has pretty good prices as long as you can get a local FFL to do a transfer for $20 or less, any more than that and its not really worth it.
If there is something that you had in mind you could check with some pawn shops. Talk with them and let them know what you want and ask if they could keep an eye out and let you know if they get one in. Police trade ins are usualy good to go for Glocks.