If you have the full version of Kontakt, you might check out a company called WavesFactory. They have very reasonably priced sample libraries that sound great.  I bought Harpsichord, Strum Guitar (major and minor chords only, but very good), Strummed Ukulele (maj and min), Fingered Ukulele (to roll your own chords and parts), Tambourine (DAW-synced patterns), Fab Bass (Beatles Bass), Direct Bass (all purpose five-string), and Flugelhorn.  They are all excellent and cost under ten Euros each.  There are also some interesting free libraries on their site.
 
I had a "missing samples" issue when loading Flugelhorn, but WavesFactory got back to me immediately and it was a very simple fix.  Everything else has been 100% bulletproof.  Several WavesFactory sounds are now on some of my upcoming records.
 
Remember, though, that you can't use these beyond demo mode with the free Kontakt player--you need the full version.  Because of the samples out there for low prices, Kontakt is the best investment I ever made.