I don't know where you're located, but if you are close enough to Lufkin, TX, there is a good sale there.  I went to their sale this past Friday, and the geldings were sky high!  I don't know how the mares and foals sold the rest of the weekend, but you can email and ask them.  It's a very well run sale, and I have bought some nice horses there.  They don't have one in July, but there is one in June.  Check out their site at http://www.havardsales.com/ 

Also, I think broodmares sell better when they are bred, because if they are left open, the buyers will wonder if there was a physical reason why they weren't bred.  If you decide to take them to the Lufkin sale, I can tell you that cow bred horses sell best, so I'd breed them to something with Peppy or Smart Chic Olena or something like that.  Good luck!