You do know that you don't need that much dirt to grow potatoes, right? Just enough for the roots to grow in.
Tater Totes. There's a short vid and step by step instructions below it (click on each of the steps for more in depth instructions). Instead of placing the totes on the ground, there's no reason they couldn't be placed on top of a pot or a small storage tub. This would be a really cool idea for small batches of those exotic fingerling potatoes of different colors that are so expensive in the stores!
Self watering pots are so freaking expensive. I've seen instructions before on how to make your own 'earth boxes' out of storage tubs, but even that gets kind of expensive and it's a little bit of a hassle. Here's an inexpensive and what looks like a fairly easy substitute. Self Watering Plant Containers
I thought this was so cool and I'm so trying this next year for salad greens and herbs. I think it would be fantastic for strawberries, too. Great idea for people with very limited space: Vertical Gardening!
Cross-posted: sorry for spammage.