I cannot remember the last time I bought lettuce as we have grown cos for years and collected the seeds. If you can put down sugar cane mulch or something like that it does keep the weeds down a fair bit. The main thing is water, if you have a tank or can collect it then that will have you money.

Try growing things to suit your area, talk to your neighbours and garden supplier. Carrots & corn are really not worth the time or energy. Silverbeeet, spinach, potatoes, peas, beans & capiscums are easy to grow and don't meed alot of water. All these can be grown in pots apart from the spuds as long as you keep a large saucer under the pot and keep them moist.