From the usual suspects probably , a MachineMart one probably half that and your local car boot sale a couple of quid . Forget the last option for a month or two though ...
The normal does 'em all G clamp style ones work if you're only doing it once but they are a bit of a faff.
You can get a perfectly adequate one from eBay or machine mart for well under £20, unless you're rebuilding motors for living should be all you need
The Laser lever/clamp one from e.g. Halfords is a bit small . I had to reverse the jaws that go over the valve spring retainer to get just a tiny bit more push.. then it still needs a gentle tap from a rubber hammer to get the collets to release.
