Here's a homemade rheostat katey made with a trip to canadian tire and some stuff we had @ home
it could have been made for cheaper but I wanted a nice plastic housing instead of the metal one that goes behind drywall and because we already had a wall outlet with a built in circuit breaker we had to pay extra for the square cut out cover (the fancy cover cost more then a regular wall outlet and duel cover)
something like this can be done as cheaply as 10 - 12 dollars with all new parts. we already had the dimmer, wall outlet and power cord