This place has Rem Thunderbolt 500 round boxes for $35. Shipping is $7 for 1 brick, $11 for 2, and $15 for 4. There's a 4 brick/day limit. The price is good through Mem Day.
That comes to about .08/round. It's not great ammo but for plinking it's not bad. Most important is that they have it in stock.
22LR AMMO

I've bought from Ammofast before. $9.99 shipping under 25 pounds.

Ammofast 22lr

aguila 500rd is $36.

I think we need a sticky thread here for guys to post where there's 22 available online.

Here are four already up and running.
Ammo Prices

Ammoseek.com is where I found the T-bolt in my OP. I'm not on a bunch of other forums, though, so I don't see some of those.

I haven't seen 22 LR ammo for several months... up until I went to Cabelas Employee price sale. Found a Remington bucket 1400 rounds that on sale cost me about 5.5 cents per round. That's cheap ammo. But it's also cheap ammo. Just happened to get lucky. Didn't make it to the store till 11:00 am and they were just putting the ammo out while I was watching. I think there were only 4 buckets in the box and I got one. Works for me.

22 are in Walmart now, but the premium stuff. Bigger gunshops have Federal Automatch for under 20 bucks a carton, and buckets of thunderbolts etc. Better that it has been for years. I burn up Norma TAC for practice ammo at 500/case because it is very good for the price.