RE: Used Black Widow or a Hunter II?
That is a tough one. Obviously I am a bit biased towards Chek-Mate, but I'll try to be as objective as I can here.
If you are going into the deal (either one) with the thoughts of trading before you even get it, as long as the BW is in good condition and you keep it in good condition, you would most likely loose at most $100--and there is a good possibility you wouldn't loose anything. With the Hunter II, same circumstances, you would probably loose $100 selling it used--although I do know of cases where a used one sold for more than a new one.
A new CM will have a full 2 year warranty on it, the BW will have what's left of the pro-rated warranty. I have heard BW is good about covering bows beyond the warranty period, and I know Check-Mate does.
A new CM can be built to your specs, the BW is available right now. Depending on what you are looking for, a new Hunter II may be available right now, or you can wait approximately 4 months for a custom made one.
The BW comes with arrows and such that may work for you; with the Hunter II you will have enough money left over to buy new ones.
My personal opinion--I have shot several of both, and I like the Hunter II better. The Hunter II was, to me, a bit smoother and easier to quieten. I haven't shot a BW with the new limbs (yet).
If you are buying it to keep, either bow should last you a lifetime, and both companies should be here for the long haul in case you have any problems.
Chad