No idea about sex clubs.
250 euros is indeed the most common price tag in Paris, specially with agency girls - which is quite close to the 200£ you often see in London agencies or the 300 francs standard in Zurich and Geneva. In some province cities, it can go down to 220 or 200, though.
6Annonce, Sexemodel and Ladyxena.fr are basically big advertising sites for indies and agencies as well.
From what I've gathered, Sexemodel and Ladyxena are a bit les reliable than 6A, which isn't fool-proof by a wide margin. Bigger pool of girls advertising in Sexemodel is probably a key reason - on the other hand, the average cost is a little bit lower, because there are more indies and more non-East-European girls there. Agencies are pretty much all on 6A (including stealth agencies who don't have their own site in the open but still have a network of girls working in Paris).
Then there are agencies, mosly Eastern European - with a lot of Russians and overall less Romanians than in London or Zurich, I'd say. Right now, the main Russian agencies in Paris would be VIP Aphrodite, RDV4U, Russian Girls for Me and Stroll.
I think Paris agencies are a bit less moronic than in London, and rely less on heavy photoshopping (sometimes, for instance with a couple of RDV4U girls I saw, with basically no photoshop at all except for hiding tattoos). On the other hand, VIP Aphrodite, RDV4U and Stroll can rely on downright obnoxious face-control system - they send you at a wrong address next to or in front of the real one, have the girl or (most of the time) one of their goons check you from afar (or actually have the guy drive his car very slowly right next to you so he can seize you up), and then if you pass their smell test, they send you to the correct address... Quality of service depends on the girl, her level of English as well, both going from stellar to totally subpar - just like with Diva in London.
The pity is that there are way less info out in the open for Paris than for London. That's most probably due to the law basically banning prostitution, which makes it difficult to run such forums. The surviving ones have way fewer reviews and seem to be a playground for trolls and touts pushing their girls, attacking the competition and touts from other networks. So it's trickier to know which girl is a good provider and which one should be avoided, a lot of them having no reviews at all.
No need to mention that reviews in 6A and SexeModel are of dubious reliability. I mean, there are a few people openly advertising to the girls their "good review writing" services on places like RussPuss-Talk.
