I have just returned from a month in the US and failed to find any 22WMR ammo or (a bit more specific, I agree) any 20TAC 39gr Sierra bullets. Including online supply, gun / hunting stores, several Walmarts (who can be damn cheap when they do have ammo) and "Florida's Largest Gun Show" I failed miserably.
The local gun store said people were hoarding everything they could get hold of and the guy in the local Gander Mountain store said they knew of "several people holding well in excess of 1 million rounds".
The only .22WMR supply I found was on Cheaper than Dirt where opportunists are selling what are normally $14 boxes of 50 for (around) $25 - $30 per box plus shipping which is more expensive than UK supply. One smart ass listed one box of 50 at $5000 - but I don't think it sold! Even Cabelas had racked up their prices a long way since earlier in the year.
Allegedly the supply situation is improving. I hope so because golf is beginning to look attractive!