Springfield's tax auction is in July. Abandoned lots and houses are auctioned off, starting at $600. Typically, in town lots are about 1/8 acre. There are a couple that are as big as 1/4 acre. Also, in my part of town (the poor, racially integrated part), there are blocks with several lots available, and some with houses. I saw a couple of bigger 1/4 acre sized lots with a house. The catalog is downloadable for $12 here: http://www.iltaxsale.com/new/index.php/county/Sangamon
Nearby, there is a fixer upper 5 bedroom plus on a double lot (about 1/4 acre) with chicken coop for $3500 cash. It's offered on Craigslist.
Our town has a very low cost of living. We bought a very livable house on 1/4 acre, and our mortgage payment is $200/month. Our town has its issues of course--racist and brutal police, narrow-minded bigots (the official dividing line into the ghetto has been renamed "Reconciliation Way"), and so on. But there are also a fair number of interesting people who seem to get it. Plus lots of good fresh local food. We invite y'all to join us. Time for the new consensus and all.