KC,
I'm using 2 different types of wired thermos, but none are duel probe.
I use 2 made by Acu Rite to monitor the temps of the cooker. these thermos go to about 360* degrees. I picked mine up at the local Ace hardware store for 19.95 a piece. I cut a potato in half, run the probe thru and sit on the shelf.
I have 4 Maverick Roast Alert/3 thermos I use for the meats. These only go to 212* I picked them up at JCPenney for 14.95 a piece.
I have a turkey fryer thermo that has a clip that I stick down through the smoke stack to measure exhaust temps. I think I paid about 4.00 at Lowes.
Some people use Taylor probes with success.
Hope this helps, with all the stores around KC, Bed Bath Beyond, Kohls (a dirty word to me) Famous, hardware stores, etc you should be able to find something that will fit your needs.