Can you buy a vacuum cleaner at Navy Exchange Stores? (hawaii)?

Yes they do have them, it is actually a 2 story store that does have a lot of things from clothes to food, beauty products to vacuums, beds to sheets and everything in between. If he can't get it there, then there is Hickam Air Force Base very close by or a few other military exchanges that he can go to as well. But best Pearl or Hickam would be the best places to go for it. There is no sales tax on the items so that can help, but the current Auz to US dollar is good for you, bad for the US. About 100 US will get you $90/93 Auz. He should price check them at both places before making the final choice. If he does have a car then tell him to go to Kaneohe Bay Marine Base and Sand Island Coast Guard Station and look there for a deal. Or call them to find out.