30 seconds on google
http://www.davidsonelectronics.co.uk/pcbrep.htm
http://www.laptoprepairspecialist.co.uk/
plenty of other companies offering this service.
I used to work for a company that manufactured mobos for various companies and they would rework damaged boards etc so it can be done, its just finding someone thats willing to take on outside work
There's a big difference between replacing a couple of capacitors, or whatever, and a CPU socket.
Looking at your second link, £99+VAT+return courier.
Assuming the job can be done at that price it's basically the same cost as a new motherboard.