[Milsurplus] Need Epay advice: refuse export buyer?

[Hue Miller]

I listed my radio with a sentence in the listing:

"No bids by "agents" for overseas buyers accepted"

The high bidder has a webpage that indicates this is
EXACTLY his business. 
Can i refuse to sell the item to him?
My original thinking was to keep a US relic in the USA.
Do i have to watch the auction continuously to reject
any bidders who turn up, that i can see i don't want?
Maybe i've just found another limitation of the auction
format. -Hue Miller