Standard £7k is probably about right for a JDM, you would be better off returning what you can to stock, I know someone that would bite your hand off for some Berks as they have their eye on mine
Trouble with a car as heavily modded as yours is that you would have to find someone with the exact same taste, and even then most people would prefer to do it themselves
If you kept all the bits as you changed them then a weekend swapping them all over will be good business, either way good luck