[sic] I would rather pay a good sum for a quality game [...]
And there's your problem right there. Your assumption that SL is a game. It's not, although you can play games there. It's a place to meet/build/whatever is your kink. In fact kink seems to be the most popular thing in SL. That or Gor sims, which seem to be mainly populated by misogynistic assholes and grandmothers who want to RP the whole warrior sex/slave thing, Having said that, you can have fun in SL in the BDSM community and even in Gor if the role playing is good.
As to the purchasing of in game content. It's not the same as in games. You're not buying from Linden Labs, but from other content creators, some of whom are brilliant.