Buying a car w/o registering or paying sales tax

Buy something slightly used from a private seller.

http://www.auto-auction-access.com/auto_exporters/auto_exporters.html

most dealers are fined by the manufacturers if cars they retailed end up overseas within a certain period of time after sale. the fines are big - often in excess of $10,000 per unit. don't let the dealer know you want to export. most will require you to register the car and pay tax immediately but some haven't wised up to that yet.

Illegal not to pay sales tax

There's no state sales tax if you are a resident of Delaware, otherwise SOL. Some states even expect sales tax when a car that you already own is brought in from a tax-free state.

dodgy doubt u can avoid just on 100 level knowledge