You could try Hydroseeding. That is the spray in grass, they spray a thick layer of theis green mulched up crap in the yard and it grows grass. A guy here at Boeing used them and he said it worked real good and was a lot cheaper than sod. The flyer he gave me says it is $100 for up to 500sq/ft, $120 for 500-1000 sq/ft and then $0.12 per sq/ft for 1000-4000. That can give you a rough idea on the cost.
THen they have special grass mixtures that cost a little extra.
I have never done it, but he said it gave him a nice yard in a reasonable short time with a lot less work and cost, now he complains that he has to mow it!!!
This is the site on the Flyer I have:
http://www.whysod.com/
That seems to tell most everything. I have done the sod route before and I will never do it again, what a ..........
Hope it helps