I debated building one but decided that the Fjellse from Ikea for $70 (now $40) was the way to go. However, the night I had planned to make the trip to Ikea to purchase it, a huge thunderstorm rolled in causing me to cancel my trip. The next day, whilst browsing Craigslist I came across the same bed frame for $10. It was missing the hardware and the bed slats, so I managed to bring it home for $8. That thunderstorm saved me $60, praise God!
Then came the hardware debate; I could go to Ikea in hopes of finding the right amount of free hardware, or stop by Home Depot and somehow replace the hardware. I chose the later. Based on the width and depth of the pre-drilled holes, I landed on some hex screws (with the letters ARK on the head). In my opinion, they're much sturdier than the Ikea hardware would have been.
For the bed slat dilemma I purchased some 1 x 4 furring strips, had them cut to a quarter-inch shorter than the width of the inside of the frame, and fastened them into place with screws.