The ATF's proposed M855 ban predictably resulted in a spike in demand and pricing for good ol' green tip, but it looks to have spread to .223 in general. We're nowhere near post-Sandy Hook shortages and pricing, but availability and price has been hurt.
M855/SS109 green tip is now in the 60 cent ballpark, which is close to double what it was going for six weeks ago. IMO, I wasn't buying green tip when it was a few cents per round more than FMJ, and double the price sure isn't worth it. You're getting into premium hunting / match / defensive territory, which green tip is not.
Should the ban become formal, I'd expect it to be in the $1/round ballpark pretty quick.
M193, which no one is proposing banning, has gone up 10% to 20% and availability is way down.
Most of the big ammo sellers are running behind - up to two weeks delay.
Looks like the spike hasn't spread outside of .223/5.56mm yet, but that doesn't mean it won't.
Edited to add: After a mass negative outcry from the public and Congress, ATF has pulled their proposed "framework". News link >
Looks like several places that were showing out of stock are now magically back in stock--learning from previous rounds of panic buying, I see. Would also expect to see some clearance priced M855 hit forums soon as "neckbeards" try to pay off the truckload of green tip they bought on their credit card!