You can get an established CAD program for less than $10:
IMSI TurboCAD 9.2 Deluxe - $7.99 free ship
For a little more, IMSI DesignCAD 3D Max v.14 - $16.95 plus shipping (free shipping for orders over $45)
TurboCAD is comparable to AutoCAD LT, though AutoCAD LT is better overall.
IMSI TurboCAD 9.2 Deluxe - $7.99 free ship
For a little more, IMSI DesignCAD 3D Max v.14 - $16.95 plus shipping (free shipping for orders over $45)
TurboCAD is comparable to AutoCAD LT, though AutoCAD LT is better overall.