If the seller implied the condition to be good...It's the e-bay seller you should be talking to, not Velocity.

I've heard of some Velocity rims suffering from cracks, but haven't seen 'em myself. Velocity may very well take care of it, but really they have no responsibility at this point. You're not the original owner and there's no telling what, or how many owners these wheels/rims have been through.

The rim damage and the crack might be related- maybe not. We have no idea whether the spokes have been properly tensioned. Those are low spoke count wheels so tension might be unusually high to insure or correct rim alignment. There's just no way of knowing with second hand stuff.

With E-bay, you bought it as-is. People shop E-bay to save money. You take a risk and the responsibilty is yours. If you can work a deal with the seller, great. If not your recourse is generally not with the manufacturer. If the hub is good, put a new rim and spokes on it. That stuff is not that expensive. Hope you got aq good deal on it!