A powered drum sander (or thickness sander) might seem a bit of a luxury when contemplating the prices of newly manufactured units. However, given that the cost of building one yourself will be substantially lower, it's a project well worth considering. See these videos for some ideas:
Homemade 18" Drum Sander by thewoodworker01
https://www.youtube.com/watch?v=KGK1OwYYFf8
V-Drum Sander Build by Paul Pomerleau
https://www.youtube.com/watch?v=vqPJQcWBmRg
Cheap!!! "HomeMade Drum Sander" With feeder. by Wooden Tool Man
https://www.youtube.com/watch?v=ggyOKU02SdM
My homemade 29" drum sander by sreza13
https://www.youtube.com/watch?v=BEsr5qpPx6o
Holesaw drum-sander by pocket83
https://www.youtube.com/watch?v=Z9nvIjrTv3E
Homemade Drum/ Thickness Sander by Simon Heslop
https://www.youtube.com/watch?v=oKM3-sFXEIM