I currently make two varieties based on the old Interfax Harmonic Percolator circuit:

1) Harmonic Percolator- this is a direct clone using vintage-correct parts (2N404, 2N3565 transistors, 1N695 diodes) - £85

http://fredric.co.uk/misc/hp_new.jpg

2) Utility Perkolator- using NOS Russian MP16B germanium and ST3904 silicon transistors, obscure Russian silicon signal diodes - £70

http://fredric.co.uk/misc/up_new.jpg

These are built to the most recent 'general consensus' schematic, with the addition of a switch to disengage the clipping diodes, for a more open overdriven sound, which adds to the versatility of the effect.

All parts are the best quality available. Alpha pots and etched fibreglass PCBs (not perf or veroboard). True bypass via alpha footswitch, powered by battery or standard center-neg DC jack. This pedal has a clear orange/red LED.

Shipping is £5 within the UK, or £7 worldwide.

Youtube demo:
http://www.youtube.com/watch?v=m1Y6HdU7PlY