UltimateBet (I know) and PokerStars (I think) go as low as 1-2 cent NL real-money games. I cut my teeth at UB 1-2 cent games ($2 Max buy-in), and just moved up to 5-10 cent games ($10 Max Buy-In).

In the 5-10 cent games, $100 is still only 10 Max buy-ins... so that's probably where you belong (assuming you aren't totally new to Hold Em and real-money games... and take it from me, Limit real-money games and No-Limit play-money games don't prepare you for real-money No-Limit games).

I've had sessions where I've had the equivalent of 3, even 4 Max Buy-Ins in an hour or two. I say equivalent, because I don't like my stack being much below 75% of the max buy-in so I re-load often for smaller amounts. Nothing worse than getting a monster hand with a short-stack where you can't take advantage.

I've been very happy at UBet 1-2 and 5-10 cent games, for what its worth.

And don't chase any site's Buy-In Bonus til you're ready for the games they offer. Those bonuses will ALWAYS be there when you are ready and properly funded.

Good Luck.