I use them all the time. And love them. Heard a rumour that they 'pinch' flat but i not had a single flat with them. I run them with Mavic 717 rims at 40+ psi maybe a bit hard for some type of ground. Good grip for mud.
UKbike store sell them i think for less than 45
£22 each Sorry don't know of any other on-line sellers who sell them
Paul not retro but the new Specialised Houffalize 1.8's are very light, a better profile and a slightely bigger cushion, they play rally well in the mud too, despite the small knobs, they self clean! £40 a set