[Electronic M]

If you have a decent sized component stereo system and a lot of RCA cables from different sources you may already have one. Quadradisc/ CD4 records require audio cable with less than 100 pF to work so when I got a few records and a decoder I took a capacitance meter (at the time all I had was my Heathkit C3 and a 100pF reference cap) and a bunch of cables I had and started testing. Shorter cables will have less capacitance and capacitance increases with length. I found I had 2 good candidates a short cable (about 2') that was just long enough to comfortably place my decoder/preamp next to the turntable, and a longer cable that had low capacitance per-foot that I'd need to cut down a bit to meet capacitance spec but could get more length out of than the short cable... ultimately I went lazy and used the short one.

IIRC most coax available from parts supply houses should have capacitance per foot in the datasheet and possibly search filters...if you don't mind adding your own RCA Jack's that should be another cheap route.