CM Sentinel 3 is a very solid mouse, is a bit on the heavy side and the sensor isn't the best available.
Another really good one is the Mionix Castor, it's incredibly well made and at the moment I cannot fault it's quality but it's probably over your budget.
If you don't want to stretch much more than £40 then I'd recommend:
Gigabyte XM300 - Pretty much a DA clone uses a 3988 sensor
CM Sentinel 3 - More palm grip shape, heavy as stated and a 3988 sensor
Zowie mice are also worth a shout but some do have a few flaws, mainly with scroll wheels not being the greatest, but most are fine and should last you a while.