Both Formula and Zipp offered wheels that came with the 10-sp only hubs, as well as Shimano. The Formula and Zipp internals were the same, and used the same deeper-spline body made of aluminum. I've answered 2 CL ads for nice Shimano wheels, and found them, upon arrival, to be 10-sp only on the rear. I've not see any manufacturer offer a replacement freehub.
I had two sets of upper-level Formula hubs, one laced to a set of Alex Equation rims and another to a set of Alex ACE 19 rims. Both wheelsets were OEM on Ultegra- and DA-equipped "packaged" bikes. Everything about the hubs was identical, but the carrier on one was 10-sp only. I took them apart, hoping to see a possible swap, and the internals were slightly different, so no-go. I still have the ACE-19 wheels, because they're pretty nice, very strong. I have a couple of extra 9-sp cassettes, and I may elect to modify one to see how it works.
Some of the wheels can be had for a great deal, for that reason. A simple wooden-handled file can make short work (an hour or less) of most cogs to deepen slots in the cassette cogs by 1mm. Like some posts say, in some cases you only need to work on 5 of the cogs; depends on the freehub.
I knew Shimano was doing that from about 2004-2008, but I didn't realize Shimano was still doing that by the 7800 series. I have a set of WH-7700 wheels and a set of 7900 wheels, plus a hand-built set with 7900 hubs. A friend of mine has some 9000 hubs. All accept 8/9/10 cassettes. Lately, I was looking on CL and saw a nice set of WH7800 wheels, which are also on eBay. The price seemed right, and I discussed them with another BF member, and he pointed out they are 10-sp only. I'm still considering it, but am just not sure. Maybe with a heck of a price break.