I've been playing w/ a nesco for a couple months now. I generally only do 120g batches in it.

I'd love something that I can do larger batches in and use w/ artisan.

I don't really know where to start tbh.

I wandered around on the forum but haven't really put anything together yet.

What's the "correct" thermocouple to buy?

Maybe one of the home built roasters would interest you; heat gun/bread machine and stir crazy/turbo oven?

https://artisan-roasterscope.blogspot.c ... ction.html lists the type of logger you'll need (Mastech likely being the cheapest) and that will tell you what kind of probe - probably a k-type.
I tried a HG-BM but found it too "leaky" and at the whim of environmental temperatures, it's underpowered for well developed light roasts (roughly 3300W needed per kilo as per Rao's book but then he recommends running at 80% capacity...). SC-TO is what I'm using now, it does light roasts really well but requires the SC element to be on and with a proper seal it's much less at the mercy of the weather.