For the most part, it's setting a credit limit before free shipping is our major concern with the "free shipping" option. Usually when there is a restriction like shipping to the continental US only, it's because the business machines the sellers uses for postage doesn't allow shipping to Alaska and Hawaii.
If you aren't using a postage machine, but are concerned it'll cost more to send there, that's not true. It costs the same amount to send to Alaska and Hawaii as it does to anywhere else in the country. (If you send it by parcel post, it takes a bit longer, but with all other shipping option it takes the same amount of time to get there too).
Ah, I should make it clear that I'm talking about USPS for the information above. The other shipping services could be different, but USPS would likely be your method of shipping anyways, lol.