Well the amount they take really depends on what they can contract with the company they are selling you to, and sometimes they will make very little money on you in order to get you in there - better a satisfied customer than not.
I will switch from USD to DKK which is what I am actually charging in normally.
I was working at a large bank and the rate was 700 DKK an hour for me and the bank was paying 725 DKK, it turns out that the bank refuses to pay more than that because well banks are often cheap I guess. So it turned out the recruiter was only making 25 DKK an hour on this because the consultant they sent before me was such a disappointment that the bank was really upset with them and they needed to make it up to them.
>In my previous contracting work I always knew how much they were making on top of my work, but if I were a consulting company I'd probably take some pains to prevent the subcontractors knowing such stuff, just because of the risk of them cutting me out.
The contracts the recruiting companies give you prevent you from cutting them out during the project and for some time after that - generally around 6 months after.
My experience is that the recruiter generally tries to charge 150 DKK on top of what I charge.
The place I'm at right now is a Swedish company, the SEK is worth less than the DKK, the recruiting company couldn't get more than 750 DKK so I took a cut to 675 DKK per hour for 6 months with a possible 6 month extension, because otherwise I would have had to wait maybe a month to get a project paying 700 DKK per hour.
As noted before you should expect to make twice as much money per hour as you do in a permanent position to take care of the risk involved and also because you have to handle stuff like your own pension, accountants etc. The risk is stuff like not have a job for 4 months, but for example if you manage to work say 2-3 years straight consulting you are obviously doing better at that point than full-time employment.
Also as noted every now and then a project comes along with less hours and that can be a good way to recharge your batteries, for example my last project working 4 hours a day 5 days a week still gave me more money at the end of the month than my last permanent position gave me (just wage money though, not if I counted in such things as vacation money or pension in which case I was behind by about 5000 DKK)
>Whereas, in the classic agent model, more pay for you is more pay for them.
yes, it's true it doesn't work like that in theory but in practice it basically ends up working like that, in my experience it isn't difficult to find out how much they are making on you per hour and then demanding more per hour. If they have a good experience with you, client happy, your renewal coming up and you say you will renew for more money it makes sense for agency to take a cut. At the point you've been working 6 months and the client wants to renew all reasonable agent risk is gone and it's pure profit for them.
on edit: clarified a point with how much the bank paid per hour.
on edit2: clarified another point about working less hours on projects.