Barry, I can't help you with a used grinder, but I think I can help with something else:
before you decide to buy ANY grinder, you have to decide whether you ARE DETERMINED to make knives or not. If you go into it with the attitude of "seeing whether I suck", then, yes, you'll suck. If you insist on succeeding, you've made the most important decision of all.
A little truth: most all of us suck at first, like with most any new thing we try, especially craft skills. Few people make a true "keeper" the first time out of the gate. That's not the objective. The objective is to see some improvement from the first to the second, to the third, and so on. A strong desire and study, practice, study, practice will get most anyone better. There is no one who's perfect at this and has nothing else to learn or improve. Likewise, no matter how good you get, there will always be someone better. But that's ok. Improving is more important than ANYTHING ELSE! Two words: Heart, and Focus!
My advice, buy the Coote and proceed with determination........
