First of all a thread about this has already been started. Secondly get over it there dude. Ten dollars I'm sure you didn't break the bank over that, plus how many other online games have you already purchased that weren't at discount prices? One game that all of a sudden has a promo shouldn't deter you from buying any more online content that is just immaturity at its best. You win some you lose some.
For example, I bought Bionic Commando a week before the price drop never came on here and complained about it, thats just looking for a b-slap. I just sucked it up and say oh well maybe I should've waited a little longer. Being ripped-off is like paying a hooker only to find out it is a drag queen.
It is your choice to purcahse a game when it first comes out or wait for a price drop or if it could become free. Don't hate on Sony's decision to make it free just because you brought it a weeks ago when it was NOT FREE.
If it was a good game for you, than there is no need to regret your buy.