I bought a couple five packs of DS18B20s off of amazon several months
ago. I have a couple sensors that I can spare, but at the time, five
packs were $11 and shipped prime and that would get to you quicker.
What problems are you having with the thermocouples? If you're using
a lot of cheap bare wire TCs and some beefy heaters, the TCs could
just have an interference problem...
--Rick