After finally getting fed up with having our mattress on one of those cheap metal "frames", and no headboard, I decided to try my hand at a platform bed and plank headboard.
I followed the headboard plans to a T, with the exception of using 1x4's for the front trim instead of molding (at HD/Lowe's, the cheapest option would have set me back $40), and making it higher and wider to fit my bed plans. Everything came together very easily.
For the bed, I drew up the plans myself. I wanted clean lines and a modern look, with short wide legs. Instead of having the mattress rest on slats, I elected to hide the box spring within the wood frame, with the mattress sunk down 4" below the lip of the frame.
Total cost for headboard: $100
Total cost for bed: $80
Do NOT waste your time going to Lowe's or HD to buy any of the 1x's. The only frustrating part of this project was finding un-warped wood, and the big box stores had me pulling my hair out. Find a local wood place in your area, give them a call, and ask if they sell to non-contractors. My local yard was actually cheaper than the big box stores, and their wood was straight as a board, as it should be.
Clear: Minwax Satin Polyurethane (3 coats)