AFAIK salaries are rather low there, but cost of living is quite expensive.
I appreciate your comment but I'm not disappointed. If being rich means working 20 hours a day for 5 years will little luck of success in the end (like any startups), I'm not willing to pay the price.
I've traveled months per year the recent years, spent a year in Asia, rided 22,000 kilometers in India on Enfield (and about to go again for 4 months) and so more much I can't list here. I feel very lucky of my current position.
However I have to say the feeling I had when living in San Francisco is as following. If I had spent as much time and dedication on my projects while living in San Francisco instead of Paris, I would have had 100 times more in return than what I've had in France. On a money level, as well as on a professional level. Might be too late now.
San Francisco see developers as the only way to achieve their project they just raised 10 millions for. You're gold to them, they accept to pay a higher price.
In Europe most young developers want to be Product Manager (or any Manager positions), most developers in SF don't care about this, they want to have fun. The reason could be you get paid super well in SF, and not in Europe :)
I can count in one hand the number of technical freelancers I've ever seen or heard about but I also have never actively searched for one. On the other hand there are a lot of companies that act as middlemen between contractors and companies. These contractors are employed and paid by the middlemen, but they go on to work directly on the client's site. These middlemen make a very decent profit since they pay their employees the usual (20-40 euros/h), while they bill them out to companies for up to five times as much. In some languages these companies have a specific name but I don't know how to translate it. I think they're a bit different than the agencies in the USA where as far as I know they take a percentage of the contractor's hourly rate.
In any case I guess Linkedin is a decent starting point. In some European countries it is used by huge percentages of the working population.
For the contractor, contracting via a respected agency means you're almost guaranteed to be paid. However, they don't really offer much value beyond that. I personally dislike dealing with them but then again, my last contract didn't pay the agent, and I still got paid.
They don't really do that much besides spam the local job sites, but being from the US you won't know the local job sites, so you can either need to invest in figuring that out or you can pay recruiters their cut.
UK wise, there are a whole bunch of sites I guess the following catch most of the population:-
http://cwjobs.co.uk http://gumtree.com/uk http://jobsite.co.uk http://www.s1jobs.com/ http://www.technojobs.co.uk/ http://www.monster.co.uk
60000e is about £50000. Inside London or working within the finance industry, there will be developers who'll be earning more than that figure, especially contractors. However, typically contract rates seem to be between £200 - £400 per day, with some outliers on both ends of the scale.