There's no need to buy any Yamaha styles especially off Ebay, there are thousands for free on the internet. I think most people selling them on Ebay are just putting their own net collection onto a CD and making a fast profit by selling someone elses work.
If you use the links on Synthzone under the make of keyboard you have, many home pages have styles on them and some of these sites have links onto others, the list is endless but the only problem is that quite a few styles are duplicated all over the place under different names.
I'm sure some kind soul on SZ would send you some Tyros styles.