You dropped the ball on this one.
I used to sell all of the time on eBay and if that was me and you sent the message then I would be okay with waiting. I usually expected payment within 7 days and would send out the invoice after the bidding ended. If after 7 to 10 days and they were a no show, I would send them a reminder letting them know I needed to be paid.
I think they should have mailed you back acknowledging your mail but who said they arent on vacation or out of town on an emergency. You should have waited on the feedback thats just a common courtesy.
Personally your getting what you deserve....
Billy