Lots of auctions have them. Use HiBid, ProxiBid, Live Auctioneers, InValuable, etc to find them. Watch out for all the extra charges. I did several of those auctions recently, and the final total over hammer price, once everything is figured in, was 25 -40%! Use caution and read everything, especially all the charges and terms, carefully before bidding. Every one is different and has very different charges and policies, as well as speed, efficiency, and professionalism in handling it, especially getting your stuff to you after the auction. Many will take a week or more to get you an invoice, another week or more to ship once paid. Others are quick on the invoice, but spend a week or two getting stuff out once you've paid. They all whine about how busy and overworked they are, but they sure didn't mind taking your money during the auction.
I've become a real expert on that crap in the last couple months, and am about done with all that. I just got one gun a couple days ago that I won at auction April 2 from Compass Auctions in TN. Old Barn Auctions in Ohio took 9 days to generate an invoice and STILL has not shipped a gun I won 4/9! Clark Auctions in TX just shipped one yesterday that I won 4/16. Anyway, you can find stuff all over the US at auction that way, but be careful. Big mounts probably cost a fortune to ship, and are probably susceptible to shipping damage, too.
There was a big annual 4-day auction a month or so ago in Iowa that had a TON of mounts. They even had one whole day of the 4 devoted to mounts, another to antlers. Circle M Auctions in Marquoketa, Iowa. But my net cost with them after all charges and surcharges was 31% over hammer on one gun and 38% on another, so be cautious.
Even our local auction house had a bunch of African stuff a couple months ago. None of it went for much, either. In fact, several things could get no bid at all. North American mounts are much more popular than African, from what I've seen.
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