I went to my local Maplins (UK electronics chain) at Regent Road, Salford yesterday and they had a large basket of 9v 200mA wall warts for £1.49. These end in a tip positive mini jack meaning that they are perfect for old Electro Harmonics, DOD, Dunlop etc. pedals. I tried one with my big muff and old DOD phaser last night and there was no extra hiss or noise.
The 2.1mm dc plug to convert for 'normal' pedals is less than 50p meaning that the total cost of a power supply with enough power to run most units is less than £2. Rememeber to wire it the right way round though.
These are obviously excess stock from some device they have sold in the past so I don't know if all branches have them.
