When I worked in Saskatoon the company I worked for used the exact same black plastic "probe holders" as cable glands which is what they are actually used for. The strain relief type have a pigtail extension to prevent the cable from breaking at the seal.

Anyways we ordered them from B&E electronics for around 50cents a piece and they come in a bunch of sizes. So $10 for something worth 50cents and relabeled as a probe holder is quite the rip off.

That's pretty much the only criteria when deciding if something can be called a hobby or not.

there is a 1/2" CPVC fitting that works great as a probe holder, it is 2 pieces with a rubber seal, fits PH probes perfectly.

yup, you can get white ones for about $7 for 10 on ebay. Im going to check the local electrical supply place for black ones still I think