I've had good experience shopping with
http://www.xxcycle.com. The Stronglight Impact cranksets they sell are a better finished version of the Spa cycles house brand; both are Sugino (RD2 I think).
But here's a hot tip: I ordered what I thought from the illustration was the Stronglight Impact Double/Sugino RD2, hot forged, nice enough but very common on top-end bikes, and received instead the rare, beautiful and altogether wonderful Stronglight Impact Compact, which is a relabelled cold-forged Sugino Cospea, a different beast altogether (same measurements and tread though). Pic on this thread:http://www.thorncycles.co.uk/forums/index.php?topic=3898.msg17120#msg17120 Also scroll down to where Dan shows his own Cospea in a high state of polish, signed!
Though I wanted only the cranks as I was fitting a single Surly stainless steel chainrings to go with my Rohloff, the crankset came with excellent lathed chainrings. (I'll sell them cheap later once I determine they aren't wanted on any of my bikes. They're better than any chainrings I've had before but it's a question of gearing.)
Andre Jute