Thank you RedRiley. Nice link!

dido that mini  mover.. detroit in the pits with their school..  tell you had bad NC dept of revenue has got.. I get bill EVERY year for $40K plus for unpaid USE taxes in importing cars from charleston sc.. seem NC DOR contacts CBP every year to see who is importing cars and then taxes them an extra $2-4 k per car..  BUT being a lic dealer here in NC.. I am EXEMPT for NC state sales tax on sales ..   later bc

Although l am not in Michigan, l find that hard to believe, Michigan is in big time financial trouble and one would think they would be grabbing at all possible revenue-

Big AL

I suspect that, in the absence of documentation of current value, Michigan might accept the original price on the assumption the subject vehicle has depreciated over time. Surprise!

I am quite amazed that DMV there in Michigan will NOT make you use the actual bill of sale for the value..  it would be considered FRAUD here in NC..  later bc  ps.. what would I know ?? only been importing and selling cars for 44 years

A Heritage Certificate or Technical Specification from BMH would probably help. Takes a little while to get, though.
https://www.britishmotormuseum.co.uk/archive/heritage-certificates

I am in process of purchasing a 1986 Austin Mini 1000.  Our Michigan Secretary of State informed me that I could use the original price of the vehicle to register it, which would save quite a few dollars.  I can use the original invoice, official advertisement or an official document from a reliable source for that year and model.  I have looked for a week to no avail.  Would anyone out there know where to find this information? Any help is greatly appreciated.  Thank you.