This is known as a thumb piano . . . I bought mine at the Armadillo Christmas Bazaar in Austin a few years ago . . . only problem is I can't get / keep the thing in tune . . .
Oh, I relate to the out of tune issue. Try a electronic tuner - - it helps - - but I still have issues.
I just do not have a good ear . . . but do tell, where do you find an electronic tuner?