How much is my car worth?

Just looking for opinion here, I know there are plenty valuation websites out there but most cost money, and I've looked at Autotrader quite a bit but its not giving me a great idea of what I could get.

I have a 2002 Petrol Ford Focus LX 1.6 in blue. Its just ticked over 70,000 miles. I bought the car for £650 (advertised for £800) on 64,000 miles. Since buying the car I have done a bit of work. In my ownership it has had new brakes, new ignition system, new wing mirror, oil change, etc. As it stands there are no known faults and it runs smoothly and returns 35MPG which, although is shocking these days (and one reason I want to sell it), is actually very close to what it returned brand new. It has 10 months on the MOT. On the outside there's no visible rust however on the underside there's a bit of corrosion, and the brake pipes will need replaced before next MOT.

I love the car and considering the price it has been nothing but fantastic and reliable. I now feel the need to move on to a new(ish) fiesta.

My goal would be to sell it for at least £600 (advertising for £700). In all honesty am I being too optimistic or is this reasonable?

If the car has the 10 months tax to match the MOT it may be worth £600 even considering the brake pipes need to be replaced. But without tax I would say around the £500 mark.

Hi so why should you get any more that what you paid for it those jobs you did are just routine maintenance jobs that you should do anyway.

Push for a grand possibly if your work added to it really made a lot of difference!