While regos for the 2017 InterAm Hash for 6-9 Oct 2017 in Phoenix, Arizona sold out in 3 days (25 months in advance!), they are transferable if you find someone who purchased but can’t attend.  Per the web site:

Is it possible for me to still buy a rego to the InterAmerica’s Hash?
No. It is nearly impossible to find anywhere to fit 2000 hashers as is. There is no leeway there to take on more attendees. However, buy from a friend! All registrations are transferable. You know the drill, with an event that sold out in 3 days 25 months before the event, I think MAYBE a hasher or two MIGHT have a change of plans and sell their rego. Chat up your friends. And lovers.
How do I transfer my registration?
If you are selling your rego, you’re silly, but hey, it’s alright, we still love you. Don’t you dare charge any other person in our hashing community even 69 cents over what you paid for it. To recap, everyone paid $199 for their rego. Sell it for that. Or less. If you don’t, you’re a jerk, and people will shame you. G see’s all and hashers certainly can’t keep their mouth shut for any number of reasons. Work out payment between yourselves, and when you and the buyer have shaken hands on it, given handy’s over it, whatever, go into hashingtickets.com and go through the transfer registration process. Done.

The Phoenix H3 is encouraging sellers to keep the price the same or less.  Once you find a seller, go to hashingtickets.com to transfer.