At least he gave you a discount, he could have said he has no stock and just refunded the money and called it even. $35 is still a good price for a mini champ. I think you didn't do too bad!
I understand that everybody makes mistakes and I generally don't worry about it if they make good on their mistake.
I've only had 2 bad experiences with eBay sellers, the first was a New $500 Motorcycle Fairing that turned up with runs in the paint, eBay did nothing to help me, saying I'm too picky and if I'm not happy send it back for a refund, $100 shipping at my cost, that seller copped a lot of abuse to the point eBay banned me for a while, the second was a $30 Leatherman Surge which never turned up at all, I'm in the middle of a PayPal dispute at the moment, the seller can't be contacted so it seems the seller was a fraud! No point abusing them since they're not even there.