I'm in the market for a k40

Hi!
I’m in the market for a k40, and then the cohesion board and upgrads. Are there any K40’s I should stay away from or just shop on price? Most seem to be in the 350-450 range and I’m wondering if there are significant differences?

Thanks,
Mary

Orion Motor Tech tends to be a good seller to order from, eBay is cheaper than Amazon, and you want the knob with mA meter, not the “upgraded” digital panel: