Yo Gabe! Glad to see you are still around
I remember talking to you many years ago, hope everything is well and you are still crushing.
Back in 2007/2008 I could clear a $50 kickback playing a few hundred hands at NL5 on the Party network, but those bonuses are long gone - and I think it was very rare to be clearing something decent at those stakes, I mean it was probably close to 50bb/100 just for the kick-back and then you got the deposit bonus too which obv doesn't release much at NL5.
Dunno if its feasible to clear a bonus at NL10 anymore, and the thing is you need to have some grasp of poker now to end up ahead... Those micro games were so soft back then, now I have a US friend who showed me a screen shot of a NL10 game against 9 players with decent TAG stats.
I would say that for NL25 players many of the kickbacks should be at least clearable, and if you can add 100% rakeback to your game then why wouldn't you? Well at least if your not from the US and hence can move money easily between sites using e-wallets.
For NL100 players and above its kind of a question of whether or not you want to go through the hassle of opening a new account, sending the documents etc just to get one buying as those kickbacks are rarely much higher than 100 bucks. The last kickback I cleared was for a piece of software that cost 120 bucks, and I just needed to rake $25 at a skin of a network that has decent traffic so IMO it was well worth it.
But yeah, take a look at the sites Gabe posted (I prefer Boogster myself as I've always received stellar customer support from there, but have used many of the sites he mentioned) and do some calculations on how much you need to rake and how they calculate the bonus requirements, i.e. if the pot needs to be of a certain size to get points (this is especially important if you play very low stakes as the pots might not often get large enough).