Looking for the cheapest possible way to build apartment units. i found this

http://www.txfactorydirect.com/

However, these are "park model homes" and I have been quoted prices of
25.00 a square foot which is about what I am looking for. They come
with plumbing and electrical. They are ready to move in. However, I
don't think the city will allow me to use anything like this.

I am looking for more great deals such as this but specifically
something I can use within the city limits. I did a lot of searching
for manufactured homes and I havnt come across much.

A frend is of the opinion that beat up shipping containers are
sometimes available cheap. I think these are about the size of the big
trailers pulled by 18 wheelers. If more square feet are needed three
containers could be assembled in a H pattern. Doors, windows,
electricity and plumbing would need to be added. getting the approval
of the zoning and city code people may be even more difficult than the
park modles or manufactured homes.  Neil

Check these, Same idea, different manufacturer:
http://www.cusatocottages.com/index_content.html