What kind of value are you looking for the s/s DMR? I would never be able to get something on your needs list as I have no access to those kind of things. At best, I could piece part a lot of smaller pets and maybe a big one depending on if I could replace it in my collection some other way.
I have access to a lot of smaller things like Argent Tournament pets (I'd have to farm the currency for alliance side..3 days per pet...but I have enough currency to buy all the horde ones I think). I can make some combination of Pierre/Rascal bots for 2 pets. I have a small amount of gold (teens) on both Llane and Madoran, so I can occasionally buy whats available there, but I don't want to go about buying large price items without some idea of what would be the right kind of thing. In place of the gold on Llane, I can probably craft one of the JC mounts (I need to check my banked mats, but I think I am good there).
It's the last in game buyable pet I need. I realize it is a stretch to ask, but figured I would at least give it a shot and see if I can even come close to what you might consider fair. I have tons of family specific stones, so any pets I have would come rare and a lot of them could come level 25.
Carry Pet Experience Reference Guide: