I am sorry to say that vacant land has really experienced a downturn in prices. If your acre has well and septic, you should be able to get $18,000 to $22,000. If you don't have septic or well, you are looking more like $4,000 to $6,000.
Currently, manufactured homes on an acre (no garage) are selling between $20,000 and $40,000 depending upon the shape of the property.
I'm sorry to be the bearer of bad news