Deepening where you are located, there's a couple of Facebook marketplace at the moment.
I agree with the others though. There was a g30 that sold on eBay a few weeks ago for more than a new model. I'm guessing because there hasn't been new stock in the UK for a while
If it's pure accuracy then thermapen is accurate within 0.4' and the inkbird 1.0'
The thermapen also has a quicker read and looks like the ink bird readout is only in whole degrees.
Not sure if that is worth the extra money to you.
Would be worried about pressure rating with thinner more flexible line and also being solid enough for your JG fittings to grab.
Would suggest 3/16 line instead.
Not sure if this is the right place, apologies if not.
I've seen a second hand grainfather for sale which should still be under warranty.. However the person selling it can't remember where they bought it from. Just wondering if there is a way to confirm with grainfather by something like a...