Starting up on a shoestring budget, I couldn't afford the expensive drip irrigation system. Plus, once I read about them and found out that the emitters often get clogged up and need to be replaced, it didn't sound like a very sustainable solution to me. At the very least, I wanted a solution that wouldn't cost a lot up front, but also that wouldn't require lots of upkeep and/or continuing cost.
I created a basic, cheap system that works really great for me. It would not work well for a large scale operation, but right now I have it setup in 7 large garden areas, approx 80x100 and it works really great for my purposes. I've been using it (and expanding it) going on the 3rd year now and never have had any upkeep or problems with the system.
It just requires simple parts that can be purchased at your local home improvement store. 1/2" PVC, 3/4" PVC, 3/4" to 1/2" T's, 1/2" pvc valves, 1/2" and 3/4" couplings & end caps and a hose to pvc connector. I lay out the 3/4" pvc across the top of the rows and the 1/2" pvc running down the middle of each row (which I make and plant double wide). I use the t's at the top of each row to go from the 3/4" pvc to the 1/2" and put a 1/2" valve in line at the top of each row so I can turn on or off a complete row if it doesn't need watering while another row may (due to different crops or whatever). Use couplers and end caps where needed. I use a 1/16th inch drill bit to drill holes in the sides of the 1/2" pvc, on both sides pointing directly at the root zone of the plants. The hose connector goes on the beginning of the 3/4" pvc run. With my well water pressure not being great, I find I can not make any 1/2" run longer than 20' without losing too much pressure, but this works out fine as I just break up my watering areas accordingly. This also allows me to have areas at the top and through rows free of pvc every so often so I can easily maneuver my wheelbarrow/cart throughout the gardens. I usually put about 6 or 7 rows on each "area". Then I just plug in the hose, turn it on and go about my other chores in the garden. 10 to 15 min later, unplug hose, plug it in to the next area and continue with other garden chores and continue that process until all completed. It has been the most efficient, low cost way I could come up with to water my garden.
I'm sure there are some other great ideas out there. Would love to hear them!