Just cleared it out!
The Watlow piece looks OK, pricey maybe? Perhaps you've found one second hand somewhere?
If you are buying new then me old mucka at http://www.tdthermal.co.uk/ can help you out with stuff at the right price.
There's a chap selling a few on eBay at the moment... (The model with one DC output and one mechanical relay - model hcjaaao​g.) Still not the cheapest PIDs going, but I worry that I'm not reading the specs right sometimes... I'm not really familiar with PIDs and I've heard a few stories about people finding that their bargain PIDs will only operate one channel at a time. Fine for HERMS, but sod-all use for fermentation control. Plus the "ramp to setpoint" feature looks especially useful for fermentation control - I don't like driving temperature changes too rapidly because it upsets the yeast, and that unit seems like it would solve that worry very nicely. Plus the option of datalogging to a PC is just the sort of thing to get my propeller spinning... (Not likely to use it in reality, but it's always nice to have the option.)
So, if I'm understanding all this, I should be able to drive my coolant recirculation pump off the relay output, and drive the heater belt via a SSR on the DC output, right?
A wee bit of advice on thermocouple selection would be handy too. I see a lot of people talking about PT100s - is that what I should be looking at for this application? I'm a little worried that most of the PT100s I can find might not fit down my thermowell...