Anyone knows where to get BL2 DLC for a good price/ for free?

Once on some Mac games site they gave "Headhunter 4: Wedding Day Massacre" DLC Steam keys, too bad you missed, and once long time ago in some Facebook page they gave free "Mr. Torgue's Campaign of Carnage", but I missed this one, but no problem because I got Season Pass after for 6€ in Christmas Sale GMG, and it was good deal, because it was same year as game released.

I suggest you getting this http://www.nuuvem.com.br/produto/1736-borderlands-2-game-of-the-year-edition-mac Steam key for both PC/Mac good price, if convinces you, buying GotY is a lot cheaper than all included DLCs separately. You also need a Brazilian address to buy there, just Google one if it asks, one guy bought this yesterday, and site asked for it.

I try to limit my "will never remember to play" purchases to $5, so it was probably foolish of me. :)

It's from the booklet inside the Totoro "Orchestra Stories" CD, "TKCA-72453" if you're shopping. But you'd probably need a time machine to find one... :)