I recently bought a Fremont Strap that I found in a store (
http://www.theukulelesite.com/freemont-ukulele-straps.html) and a Hug Strap that I bought from Outdoor Ukulele (
http://thehugstrap.com). I may also start installing strap buttons on my ukuleles, but I want to know where I want them before I do so (the bottom button is pretty self-explanatory, but the top button is a potential issue (or even deciding if you should use a top button at all).
My only negatives about the Hug are that you can't switch it to another ukulele very quickly, and that it attaches on the headstock above the nut (as would any button strap with only a bottom button) which can interfere with my hand position on some chords, like B-flat.
So I think you'll find a good option to try here.