eBay seems to be overflowing with glockenspiels, but there are hardly any xylophones on there apart from the kids' variety.

One thing I found when I was recording Box is that it's much easier to find your way around a piano keyboard than a diatonic zither, where all the strings look the same - I pretty much had to keep practising until I was hitting the right strings from muscle memory. Perhaps a chromatic zither should be my next fantasy purchase.