I just made a pepper planter for the cook (As you value your quality of life, keep the cook happy). It's the same thing I'll be doing for the figs when they up-pot and need more room. So I thought I'd show some construction details.
To get even watering to all the bags the bottom needs to be level. The easiest way to do this is to set up two level rails that you can work a scree board across. Trying to just trowel it will take all day.
If you don't buy premixed, you'll need a modern efficient mixer.
Fill bags and plant. These are the WalMart reusable grocery bags. They cost 50 cents each, $2 for the pool, I used local dirt and composted cow manure. I haven't figured the perlite, sand, and peat (mulch) but they weren't much. You're suppose to surround the bags with pea gravel to keep mosquitoes from breeding in the standing water. I don't have any pea gravel but I do have bark. So, I may use that, or, I may just let it dry out a bit every few days.
When I see how my mix wicks I'll put a hole in the side of the pool to set the max water depth. There are float type automatic waterers you can use but I'm just going to water by hand for this small a setup. I have a raised bed that's getting overrun with Johnston Grass and I'm thinking of digging it out, lining it with plastic, and going to this kind of setup. If so I'll probably put an automatic waterer on that.