I have read some posts recently about Agencies and for newbie punters in particular I want to clarify a few facts.
An Agency is run by a pimp who by taking a cut of a WGs fees agreed or not is controlling prostitutes for gain which is illegal, though neither the WG/s or punters are breaking the law unless the WG was proved to have been underage or being coerced.
A pimp can run an Agency from their parents back bedroom, i.e. from virtually anywhere as all they need is a computer and a mobile, they don't need expensive offices or indeed any business premises, if the deal is the WGs have to supply the premises, if the deal is the Agency does that then the pimp is also running a brothel, also illegal of course.
Agencies offer a punter no more protection from a bad punt than any other form of punting, because they call themselves an Agency and have glossy pictures on their site doesn't mean the WGs featured exist or offer a good service. The only way of finding this out is on here by asking punters you find credible. Agency reviews cant just be blindly believed as the pimp could of posted them online themselves, again UKP is the place to check out reviews.
Don't place your trust in an Agency just because their site looks professional, all that shows is the pimp or someone they know can put such a site online.
In my area, London, Agency prices start from about £150 an hour generally, check out the Wiki about Agencies and posts by Jason that are helpful and informative in my view. In the same areas or outside the central area of London there are A/W WGs who are charging less BUT have good reviews on here, ask yourself what does an Agency offer me that an A/W WG doesn't. In my view an Agency might have a number of WGs on offer and/or might be open 24/7, I don't need either option but I know its handy for some punters. For some punters they can build up some trust with the pimp so this can be another advantage for some.
Ultimately in London anyway Agencies ensure the prices they charge are high because they want their cut and factor that into the overall cost of course.