why spend all that money?? 
the sensors you're looking at is a regular potentiometre (slider)
like this one http://it.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=8796157&N=401
the one in the link costs 4 euro and you can interface it following this article
http://www.arduino.cc/en/Tutorial/Potentiometer
let me know how you're getting on
massimo