SRAM / Campagnolo / Shimano Compatibility

All,

I have a pair of Roval Rapide carbon road wheels with a Shimano deep-splined freehub body.

Believing that Shimano and SRAM were fully compatible, I bought a SRAM red cassette. Unfortunately, due to the deepness of the splines, the cassette won't fit onto the freehub.

I have found 1 retailer (Cyclestore.co.uk) who can sell me a replacement freehub body (Roval Shimano 9/10 15mm axle DT Swiss 240 powered) ... for £80 which is quite a big hit to take.

The only other option I seem to have is selling the Red cassette and buying a Shimano cassette which I didn't particularly want to do

Are there any other options ? Is there another freehub body which will fit a SRAM Red ?

Thanks.

Just to be sure, does the cassette go some of the way onto the freehub body, if so it may be a weirdass Shimano DA freehub body that was only intended to take DA cassettes- for one year (AFAI remember) they tried ally as a freehub body material, albeit with deeper splines- but went back to shallow splines (and compatibilty with all Shimano cassettes) and Ti for DA bodies the next year.

If you need the DT Swiss Shimnao freehub, you might be able to find it cheaper?