The A&N on GI looks like BV3-OQ4-CC2.5 for $4860. Sure in the ballpark.
http://www.holtandcompany.co.uk/Go to the Holt's homepage and follow "Buying with Holt's." You can go to the auction, send (fax) in a commission bid with your top offer, or get on the phone with one of the Holt's staff to hear the bidding and submit bids. If you go live on the phone, do note that British auctions move right along with no lingering on final bids. When the room stops bidding, the hammer falls (they try for 100 lots/hour); he who hesitates is lost. If you think you are going to buy, I'd pay Dig Hadoke to look the gun over and help arrange export to you. Do have you finances in order as the auction house expects payment promptly (I find credit cards to be the best). Do note that the H&H could exceed the top estimate; keep in mind that this is an auction, not retail prices.
If you miss, there will be more auctions with more guns. Frankly, I'd suggest you take a deep breath and study the Holt's on-line catalogue in depth, review the prices realized after the auction, and come to a very lear understanding of what you really, really want. Then, watch retail dealers and auctions for it. Buy only when you are getting exactly what you want at a price you know to be OK.
Post back if any of this raises additional questions.
