By far the cheapest KVM switch solution I've found and its a quality make (Belkin).
Bought one of these myself and it works a treat :-) Now got one Keyboard & Monitor for 2 PC's :-) Its a Europrean version, but as no power supply is needed it makes no difference. Comes boxed as new (if a little dusty).
You need the KVM switch for £4.19 plus 2 x SOHO cable sets for £1.19 ea, P&P (£4.95 unless you buy something from their free shipping section) takes the total deal to £11.52 delivered.
They also do 3m cable sets for £2.69 ea if you need a longer run.
Recommend putting KVM into their search option for the full list.
Part numbers for the £11.52 deal are :
KVM Switch : BELKIN-01117
Cable set : BELKIN-01283
Optional 3m cable set : BELKIN-01076