We're building a cob home. It's 75 sq ft with a loft on either end. We have probably been building it for approximately 5 months and it is now nearly completion with just the roof to be placed on. Our total cost todate is around $800.00 and that does not include the steel roof we need to get (hopefully salvage). The logs we are using was last years firewood. Sand we retrieved locally, it was a five minute drive down the road, the owner charged us only for having to use his loader to dump it into our truck, which was $80. Then the 3/4'' rock we had delivered was about $400. 10 bales of straw ($50) 6 tarps ($42) misc items total ($100).
We estimate the grand total may run us to about $1000.00.
If you want to check out our progress, I have a link to our website on my profile page.
Looking forward to seeing what your final decision will be.