You can have it in your shopping cart and if someone else buys it, it'll get removed from your cart.
I found one soon after 1300 EST, put it in my cart, was logged in (and had my credit card info saved on the site from a previous purchase), but when I went to check out, it asked me for my card's security code. I forgot I needed that, I ran over to my desk to get my card, and by the time I got back, it disappeared.
Luckily, I saw it again on the site and was able to secure a box. I saw it 4 times total, I was hoping to find the boris (but I don't even know if they're doing the same thing for the boris). I didn't try to buy another drac box, as they said limited 1 per customer, plus wanted to give others a chance.
But it does seem like multiple boxes are up today.