Don't be worried about the high milers - I've had several all of which have had over 100k and none had any problems whatsoever, nor are they a problem to sell on.

Nath's E34 would do you if you don't want to spend much money (as it's for sale) I know it's OK because I went with him to buy it

If you want the E39 then the market is flooded with them and they are available for very reasonable money.

Depending on your location, try viewing some of these auction houses that I use:-

www.british-car-auctions.co.uk
www.shorehamvehicleauctions.co.uk
www.manheim.co.uk