There's a company (http://www.ultimasports.co.uk/canam/index.html) that sells kit super-cars. According to them it takes 40 - 80 hours to put together what is essentially a car that is 95% as good as some Italian machine but at 10% of the cost. Not bad considering what you are getting.

Assembling a batch of nice fresh parts is a lot easier than you think. Unless you have to assemble/rebuild the whole engine by hand, you will probably spend more time waiting for the paint to dry than you will putting it all together.