There is NO need to buy an expensive circle jig, PERIOD. Just do what you were doing, only make it stable. I have used long sticks, etc many times, and did wonders.
I'm NOT a fan of expensive jigs, I get all these woodworker sale flyers in the mail, and they are full of TRICKS OF THE WEEK, that you don't need. IMHO. $600.00 for a sharpening machine, HUH, a bench grinder with the right stone is just as good. That's just one an example of wasting money, IMO.
Just today I sharpened my lathe tools on my belt sander in 15 seconds, and they cut like a charm.
Dale in Indy