Martin Style 1
Style 1 ukuleles are only slightly different to style 0 ukes. However, a quick look at the fretboard will let you know which style you are looking at. A Martin Style 0 ukulele will have only one spot at the seventh fret, while a Style 1 ukulele will have a double fret marker.
Style 1 ukuleles were made in both mahogany and koa wood - with the koa wood being more sought after.
Mahogany Style 1 ukes will be a little more expensive than a style 0 (up to $700 or so), while a Style 1K can fetch up to $1,000.