Beautiful car and good luck with the sale, but I have to agree about the price being a bit steep. The thing with mods is that if you find the real enthuisiast who wants a Z4M and appreciates the mods then they'll pay the premium. But to people who are more generally looking for a sports car, they'll go for the newer, cheaper car as the benefits of the mods is lost on them and not worth a £6K premium in this case. Also don't forget that many people will look to run a car like a Z4M with a warranty and that will be more difficult or more expensive with the mods. So your average sports car buyer with pockets deep enough to pay a premium for the mods and higher warranty costs will just go get a 911 or something with warranty. I think your target market at that price is very small, especially in times of a recession, however I hope you find the buyer who truly appreciates it and you get your asking price. 
