my thoughts;
 
 You can a buy a  fortigate anywhere and uses it. It' s probably cheaper due to American-taxes vrs VAT charges in the EU area in general.
 
 
 
 E.g VAT in UK can be 15-18%  or more , where as sales taxes in  Florida/USA is aprox 8.5% depending on county location
 
 
 For support contract, your best is to buy a support contract from a vendor in  that country that you plan on operating. I had problems where I had to ship an appliance at my own cost back to a USA vendor in order to get support.
 
 You will also need to check if you would have to pay  VAT  upon arrive. Example I order something in  the USA and shipped it via DHL  to London and had to pay VAT on top of the  USA sale-tax. So I got hit twice with added taxes that I didn' t take into consideration.
 
 So be careful and check all of avenues b4 buying. I would look at  Amazon or Ebay and a UK dealer if your in the UK and just buy it. Unless your taveling to the USA o vacation and business,  than pick up a few stuff them in your bags
 

 
 I personally don' t think there' ' s any shortcut  with eliminating value-add-taxes completely. You will pay the systems at one of  the pond in VAT, Shipping or other costs.
 
 Do your math and planning.