Well I can tell you, I mostly purchase new pieces of equipment for a few reasons:
1) I'm left handed (hard to find LH drilled stuff)
2) I throw 16 lbs. (Harder to find LH and 16 lbs.)
3) I don't know how many games stuff has truly been used
Recently I was able to find a seller on eBay who was not only LH, but also threw 16 lbs. He was selling off his entire arsenal, and had some goodies including a Sauce and Agent Orange. I had set prices in mind for each, and if they went over, I didn't buy them. The Sauce went for too much, but I got the Agent Orange for $80 shipped.
All I had to do was plug and move the thumb up and add new finger grips. $20 total, so $100 for the ball, when the online sites are charging $189 so with drilling $229. The ball had like 2 little scratches on it.
Of course the problem I ran into which was discussed in the Lane 1 form is that I don't know the pin to pap measurement on the ball, thus not knowing exactly what type of condition the ball would be good for. Also I'm not 100% of the surface, but was told it was 1000 grit.
Anyways, I don't see a problem buying used and experimenting with covers and drillings. The bonus thing for you is that the ball is free so you won't be putting too much into either one finding out what works for you. I see that as a win-win situation.
Also you never know, just like me, one of those used pieces could become your go to ball. The Agent Orange for me is now mine. It rolls beautifully, hits very well, and allows me to play in my biggest comfort zone. I've only had it for 6 days, and already have shot 297 and 279 with it, and I'm just learning how it rolls. I see good things in the future, all for taking a chance on a used piece of equipment at a good price.
Moral of the story, try the used ones. You really have nothing to lose.
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Ahhh Disco Biscuits!