I know some others here have had their eye on this one. Winter Soldier Steelbook (Best Buy Exclusive) is now $24.99 ($5.00 off) and available for pre-order for in-store pick up. These things sell fast and if you tried to get a copy of the Thor: The Dark World one you know how difficult they can be to find release day.
BestBuy.com was giving me a lot of trouble today (cart wouldn't load). If you have the same issue try checking out at m.bestbuy.com instead.
Also of note:
It's worth noting that next week, Best Buy has a promo where if you buy Captain America: TWS + a $14.99+ TV show, you get $10 off Captain America: TWS.
This will probably be stackable with the 'buy 3 TV seasons, get 25% off' promo, which is continuing next week.
Don't forget Agents of S.H.I.E.L.D. Season 1 comes out Tuesday as well (Target has it for $39.99 on Blu, Best Buy appears to have it for $44.99 barring any sales release week). May be possible to pre-order the Steelbook to reserve your copy, cancel in store pick up once in the store and then get it with Agents, with price match to Target for a grand total of about $55. At current Best Buy prices it would be ~$60). YMMV on a couple of factors of course.