Which presently converts to about GBP38. In perspective, this would push the RRP of a class 50 to about GBP128, and I would guess the sale price would be about 10-15 pounds cheaper depending on where you get it from. You certainly couldn't offer it as a standard, but as an option would be worth considering, especially given the sound works in DC as well, and given the price of a normal decoder is about GBP20 and a seperate sound equipped one upward of GBP110 with British sounds encoded.
Actually this is especially interesting in view of the claim that the high prices charged for sound equipped decoders are necessary to recover the costs of recording the sound. Yet I wouldn't imagine recording train sounds in Australia would be so much different as to justify the wide variance in cost, as well as the fact that the population of Australia is a third of the UK, and therefore presumably the size of the model market. (Actually I would argue that the UK model market proportionally would be slightly higher given a perception I get that people in the UK are more passionate about trains that people in Oz, as well as the significant market for UK trains outside the UK. My understanding is that Oz is Hornby's second or third largest market outside the UK for British models not including those bought by Australians from UK shops, I doubt the reverse applies!)