Class 3 weapons (automatics) are completely legal in the United States.
The easiest way is to contact a Class III dealer in your state. Once you contact the dealer you will discuss what you’re looking for. The dealer may or may not happen to have the particular item in stock but he/she should have the contacts to find you what you’re looking for.
If the dealer has the item in stock the paperwork process can be started immediately.
If the dealer has to locate and get the item for you the process is slightly more complicated (for the dealer, not for you). Assuming the item is in stock at the factory, (this applies to items available for new purchase, NOT to machine guns) it will usually take the dealer 3-5 weeks to get the item in stock because the transfer from the current owner to your dealer must first be approved by the ATF and then shipped. Machi2e guns are purchased the same way but NONE are available for purchase new from the factory. They will have to be located differently; your dealer will do this work for you.
Once the dealer gets your item in stock, the paperwork to transfer to you can begin. Once the ATF receives your transfer request they usually take 30-90 days to process it and return it to your dealer.
Once ATF approval is received by your dealer you will be contacted to come in and pick up your item(s).
If you wish to save some money on a machine gun you can do the legwork yourself and locate one for sale, negotiate whatever price you can and then contact your Class III dealer to handle the transfer to you. While this will potentially save you some money, there are lots of pitfalls and plenty risk of loosing your money doing it this way. It is HIGHLY recommended that unless you really know what you’re doing in the Class III arena you go through a reputable dealer to insure a safe, smooth and risk free transaction.
Understand that $200 tax is the cheap part – most automatic weapons have skyrocketed in the last few years and with the new administration taking office ALL gun prices have gone up. A M-16 will run around $10,000.