honestly..I hate using chokes, comes back to my audio install days....most of the time...its just a bandaid on a problem...may work, may not..rerouting and better grounds have always been my favorite....but you can get some snap on chokes from radio shack and some other locations, another cheap as hell source is old pc power cables, a lot of those have the chokes on them, look at some and you'll see em on there...you can pull those off and use as well.....
good luck