Porn Stars
what do you mean by "anything _above_ FS requires additional"? are you talking S&M, bizzaro videos, what?
what i understood from your post (and i may be wrong) was that perhaps one doesn't even get the bare minimum FS for that kinda price. if so, then i'd have to say not really ... IMHO, starLETs (as opposed to stars) damn well better be putting out FS (with enthusiasm!) if they're asking $600! LOL
you can get B-list stars (however that's defined) who do in fact offer everything for that rate and who may have in fact done 50+ movies and maybe even been on a boxcover or two
case in point is Samantha Sterlyng, who thru my rose-tinted spectacles is slightly more than B-list (but that's all semantics/BS anyway! so let's not even go there 
and btw, you can bet every penny of that $600 that i've done my research on her, her reviews and her services (and via email) in preparation for taking the plunge!
Actually that's a good point, but just not the one I was making. My point is and I will use Deja Chan in LA as an example. She is a Porn Star, but looking at her reviews I don't see the PSE. BJ covered and no backdoor action, just FS. Not saying that I would not see her because the other options were not available, but maybe my idea of PSE is off, if so please correct me. It's sort of a gray area anyways, open to ones interpretation. I think your idea of reasearch is the best option in any situation. BTW I think Samantha is hot too
in my book CBJ does *not* a PSE make (anal, covered of course, is another issue) and that's just my not-so-humble opinion (and i don't think i'm alone on this).
especially seeing that there are so many regular providers (and PSE wannabes) that give BBBJ at the drop of a hat ... i mean hell, you'll even see contract pornstars that do CFS on camera but readily indulge with BBBJ in the same scene, so ... what's a hobbyist to think/expect?
in the end, it all kind of comes down to the services/prices that make sense with you. there's ample debate on this board (and others) as to what exactly is a PSE! ... some people have even posited that originally PSE stood for Pornstar ESCORT and not "experience" (ruling out mere "private shows" and other such nonesense)
btw, look for my own review of Samantha in the coming months