A
real Ecomodder would push the Blazer to 20 mpg around town and be done. Convert to 2wd, slam it and drop in a TDI/6-speed. That ought to do it.
Somewhere in your town, someone has a very nice, suitable car but they have problems (marriage gone bad or whatever) and they need to raise some cash quick. Find that person. Don't look for just anything. Define your use case. What's suitable for a commuter may not be for hauling materials from the home building center.