Wheels & Encoders

Good day, Ok...I'm looking for wheels, motors and encoders for my arduino project. My choices that I can find are the Parallax $280 package or VEX wheels and encoders. Wheels - 5" - 8", all terain. (Outdoor) Motors - ~100 RPM, 9 - 12 volt, good outdoor performance (Torque) low speed. Through grass over small rocks and small inclines Encoders? I'm open. Must work with Arduino.

Does anyone have a suggestion on where I can purchase these items besides Paralla or Vex?

Not a lot of detail here as I'm looking for suggestion on where to shop. If not then I may go with Parallax.

Thanks Randy

Check out Pololu: http://www.pololu.com/

For higher power gearmotors and different wheels:

http://www.surpluscenter.com/sort.asp?catname=&byKeyword=yes&search=gearmotors http://www.surpluscenter.com/sort.asp?catname=&byKeyword=yes&search=wheels