Quick and Dirty Tips discusses the pronunciation of our favorite instrument and other grammatical concerns related to it…
‘While most American mainlanders say ‘yoo-ka-lailee,’ any Hawaii resident will tell you that the correct pronunciation of this Hawaiian word is ‘OO-koo-leh-lay,’ and this is, in fact, how it is pronounced throughout our great state. No self-respecting Hawaii resident would say ‘yoo-ka-lailee.’
http://blog.quickanddirtytips.com/2011/09/07/a-ukulele-or-an-ukulele/