Boricua, the plastic guide bushings came with the Craftsman sign kit. They fit my Craftsman router, and yes, the bit trimmed the inside of the guide bushing a bit. Maybe too much side pressure from me? Someone else mentioned the plastic guide bushings being in the Lee Valley kit, and equally useful. This is why I was thinking of using my Bosch 1617 plunge with good collars.
Shawn, Sears sells the kit for about $20. Rockler is about $40 and Lee Valley charges $55? Far as I can tell the Rockler and Lee Valley Tools sets are identical. The Craftsman kit is too, except the guide bars are shorter. Craftsman lets you align 8 pieces of letters, numbers, etc while the others hold 12. The instructions are clear. The jig is easy to use. If you live near a Rockler or Woodcraft store you could ask for a demo of the set up and use.
PS It really helps to list a State/Province & Country in your profile. This way people can try to give specific answers to your location. Our forum members are world wide.