Well, let's just cut to the chase - living on the cheap is challenging here...but living in simple abundance is really what it's all about when one comes to Kauai - here are some helpful tips.
LEARN THE CULTURE:
Be Respectful - Malama Pono = "to righteously care for"...attempt to learn Hawaiian and Pidgin. Don't try and speak it until you've been here at least 6 months if you are fresh oudda mainland, brah!
http://www.wehewehe.com - excellent online Hawaiian dictionary.
http://en.wikipedia.org/wiki/Pidgin_to_Da_Max - HILARIOUS and will make more sense to you after you hear it and can decipher...talk to a kama`aina and get the ear for it. It took me about 6 months of just HEARING it to understand it. Eh, You Da Kine, Ah? Now, I can go in and out of it pretty good.
GIVE IT UP:
Have a discussion with yourself - living here is much, much different than being a tourist, you can't just drive and see your family if you have NO MONEY or are the WORKING POOR...it can be done, live simply. There are lots of wealthy folks too. Be ready to do a menial job in order to make it. Sometimes 4 or 5 - which I currently do. TRADE/BARTER works really well here on the Garden Island.
Be ready for a big change: weather, culture, language, healing arts are here...and yes, BEAUTY!!
No mainland life here...it's limited in the consumerism of the mainland...if you want that go to Oahu. Leave with little to no "baggage" seriously, you can find worldly possession crap here....
http://www.kauaihumane.org/thriftshop.asp - one of my favs...clothes, some household goods
http://local.yahoo.com/info-21857211-tlc-consignment-boutique-kapaa - Good designer finds..reasonable, appealing asthetic
http://www.kauaihabitat.org - LOTS of furniture, clothes
HAVE A HOST THAT CAN SHOW YOU ALOHA PUMEHANA, YAH?
Don't just show up here...and stay, have someone here for you that can help you acclimate and get to know people. More people in my interaction go back to the mainland because they cannot handle it. Do come for a visit stay for a few weeks, then make your decision if at all possible - unless you are ready to make the leap of...ahem...faith.