If you are going to do some reseach on old tackle please be aware that it is addictive, and you could end up buying more than you sell....................
On the Mitchell 300.....
I searched for and bought a good (reconditioned) late example (1981) with two spools on ebay in November last year for £21.00. Mine is in perfect working order with good paint.
£20/25.00 is about the going rate for a good one - very common 2nd-hand - they were very popular in their time.
For more info on the Mitchell go
here
The Beaudex reel may be worth £20 on a good day - it is not in great condition. Don't get too excited about the inflated prices for these reels on ebay - the £40 and £50 ones just don't sell.
A JW Young reel will generally (but not always) be worth more than a Shakespeare reel with the same name (ie Condex).
I like the look of that carp rod......................