Here is a solution I came up with for a car mount for my iPod Mini, which cost me all of $3 or $4, if you don't count the tape deck adapter (which I already owned, from a previous use of a portable CD player) and power cable. Here's a picture to start with:

At a hobby shop, I found a strip of sheet copper about two inches wide and a foot long (I'm guessing measurements, since I don't remember exactly and I'm too lazy to get out a ruler). I'm not a handyman, and had never worked with metal before, but it was an easy matter to bend the strip at about a 90 degree angle over a piece of pipe to get a nice, gradual curve instead of an ugly crease.

Next, I wanted to cut a slot to help hold my iPod belt clip in place. Let's start with a couple pictures:

The idea here is that the little hook on the belt clip, labeled B, should fit into the slot in the metal strip labeled A. I clipped the belt clip to the strip and marked where the hook rested. Then I drilled a couple holes and used a small file to join them into a slot and square it off. By itself, though, this proved to be a bit prone to annoying plastic-on-metal rattling noises on the slightest bumps, so I wrapped the end above the tab with some self-adhesive felt.

Mounting the thing in my minivan was the most difficult part. Here's a photo showing the underside of the site, with the ash tray drawer temporarily removed:

I started by removing ash tray drawer below the tape deck, then removing the metal frame that holds the drawer, which is visible here. Next, I slid the end of the strip of copper into the space above the frame and put the frame back in. I made sure to choose a position where one of the two mounting screws on the frame would have to go through the copper, and drilled a hole to pass the screw. The end result is quite secure. There is only a little springiness at the iPod end on bumpy roads (which is probably a good thing).

The wire you see wrapped around the base is from the tape deck adapter -- I wrapped it to avoid having it hanging on the floor and possibly getting tangled in stuff. The power cable is short enough, and coiled, so that I don't worry about it.

Anyway, the point here is that it's quite easy to make an iPod mount with a little patience and a few dollars worth of materials, even if you're not particularly experienced with tools. If you screw up, you've only lost the cost of the strip of metal. It's not wonderfully pretty, but then, neither is my van! And it's wonderful for road trips with the kids, who are still at an age that they like to listen to Mom and Dad's music... ;-)