Buy SNG & Tournament Hand Histories
Some poker rooms consider buying hand histories to be an unfair advantage. I don't have the time to stay up to date with the changes the poker rooms make to their T&Cs, so be sure to check them yourself.
List of sites where you can buy Poker Table Ratings hand histories.
If you're ready to buy sit and go hand histories, we suggest buying from Poker Table Ratings. They have competitive prices and PTR delivers your hands quickly. Let's not forget that they're the only site that offers SNG hands -- so you don't have much of a choice anyway. 
Buy SNG hands from Poker Table Ratings.
Sit and go's and multi table tournaments are popular games. In fact, it's how many players got their start playing poker (it was for me). They started by building a bankroll grinding sit and go's or by making a nice score in mtts, and then they move to cash games since there is a higher and more consistent ceiling for profit.
Despite the popularity of these games, datamining sites didn't mine and offer hand histories for them. This comes as a shock to me, especially since there is plenty of useful info SNG players can use.
What kind of info is helpful? Well, what isn't helpful? Having data in a SNG is huge; no different than having data in a cash game. Data will give you an idea right away who's a reg, so that you can adjust your pushing and calling ranges. If a reg or good player shoves, you know you can call wider than normal. If there are good players left to act after you, then you know they'll call your shoves wider, which should cause you to tighten your shoving range. Table selecting is important to do in SNGs too.
Although data mining sites didn't use to mine for SNG or MTT hands, I'm happy to say that things have changed some. There is a site out there that mines and sells hands for single table tournaments. While there are improvements that can be made, it's just nice to see that someone has decided to take the initiative. I talk more about this datamining site in detail below
SNG & MTT Datamining Sites: Poker Table Ratings
Poker Table Ratings is the only site to offer SNG hand histories. And as of 6/29/2011, the only site PTR mines SNG hand histories from is PokerStars.
This makes some sense since PokerStars is still the largest online site in the world with 75k+ players at any time, even after Black Friday. Hardly any other site can compete, especially when it comes to the number of sit and go's being played. It'd still be nice to see other sites being offered though.
At the moment the majority of hands are going to be no limit. I did notice some pot limit and fixed limit hands available, but you'll have fewer packages available, as well as fewer hands mined overall.
The games covered include anything that is a single table -- heads up, 2, 4, 5, 6, 9 and 10-max, knockouts, double or nothing and turbo. Stakes will range from $1 to $114. The one thing that you will notice is that there are no multi table hand histories available, either for sit and go's or tournaments. I hope that this will change in the near future as these games are played just as much as the single table games, if not more.
Prices for SNG hand histories will start at around $15 dollars for the smallest package of 200k hands. It'll climb from there to where you can be spending $200+ for hands, but this of course is for 3-5 million hands or more.
Summary: Where to Buy SNG Hand Histories
Well, as I mentioned above, you don't have an option as to where you buy your SNG hand histories. You either buy them from Poker Table Ratings, or you don't buy them at all. And if it's the latter, you'll have to mine them yourself, which is a painfully slow process, or go without.
Thankfully, Poker Table Ratings is one of the best sites to buy hand histories from, so there isn't much of a reason not to buy from them. They have good prices, support, hand coverage and quick delivery of purchased hand histories. You can't ask for much more than that.