My list of "dream" ukuleles continues to shrink. One of the ukuleles on the list was a Martin--I wanted "a" Martin. A used S1 popped up at a local second-hand music store, and was priced right...and I bought it. I did put Gotoh UPTs on it, and tried to get the black nut and saddle that were used on the centennial version with no luck (which reminds me that I need to contact someone about that again).
You can find used S1 models from time to time under $300. That's really the way to go about it.
That said, the CK-39 (concert) really appeals to me (concert is my preferred scale) but I have to put off some ukulele acquisitions for a while...our Highlander needs new tires ($700)...