I am using a Paragon kiln for my heat treating. But, and a big BUT, I got mine for free. It will work, you can control the temp within about a 10 degree swing if you sit and baby it the whole time (very time consuming). I use a Fluke multi-meter with a temp function on it with a thermocouple going inside. Now the BUT, it sucks a$$ having to open the top to put blades in and out. It's not too bad for carbon steel temps, like below 1500 deg, but I just did a stainless blade at 1975 and it is scary to open that lid and reach down in there when it's that hot. Fortunately, mine is a stackable style, so I can keep the sidewalls shorter than the one you're looking at.
The price, $300 is way too much for you put up with the hassle for making knives. I've seen them on Craigslist before for less than $100, and I even bought one at an auction once for $10 (turned out it didn't work). If you could get it for next to nothing, it would be ok for you get and heat treat a few blades until you were sure you wanted a real oven. I'm still new, but I'm enjoying this hobby enough that I will probably go ahead and buy a real oven in the very near future. My advice, pass on it. If you see one for $50, that might be worth trying, but it'll still be a pain in the.....