SF Turbo 1999, what's it worth?

So, I own a 1999 2ltr sf turbo, beautiful car. Black with a touch of metalflake in it. WRX discs and calipers, whiteline bushes,Manual. Reconditioned rear subframe. Always looked after etc etc. 145k miles. cam belt changed, oil etc changed. Cleaned every weekend. I love it.  No probs with it. My problem is that I use it as a daily drive to and from building sites with shovels etc in the back and in the 5 years I have owned it the inside is getting a bit knackered.  I have an opportunity to buy a non turbo sf so I can use this as my daily drive and only use the sfturbo occasionally. As I am sure we all know taxing and insuring a car that we don't use much alongside a daily drive adds dosh so I am trying to establish this potential purchase to my self and my other half.

I looked a while back ( it was after a couple of beers) on a dvla related site and it seems as though there are only 8 manual sf turbos left registered in the uk. So if my scooby was a capri or cortina it would be worth £10k plus. Which I realise my foz isn't.

So , what do you think my scooby forester (1999, heated seats,aircon, boot roof spoiler, peddars rear shocks, no rust, ) is worth ? 

I don't want to sell it but need to have some idea as to whether you think it's worth some dosh?

Wot do you recon?

Wilbs