Difficult one as I haven't seen one of those on the forums for a while - and I have been looking.
(Currently tempted by the chance of getting a 65st50 for about £900 but I don't know if that will be too big in the room or too big to transport in the car.)
I really want a set like yours so I am tempted to say just £100
but hopefully the following is an honest view.
The last few Ebay prices for something very similar may give some indication - although what I have learned is that prices seem to vary randomly with some great deals and some very high prices for similar items. (They are in order of most recent first.)
55VT50s with 12 months guarantee for
£579 each - Panasonic Outlet sold 2 of these. They have no more though and they went quickly. No telling when they will get any more.
55VT65 for
£610 without a stand and from xs_items who are a box shifter and it is difficult to know how good condition it was in. (Returnable but no guarantee.) I have bought things from them and they were actually better than described.
65VT65 sold for
£1070 in a private sale - did seem a very good price though.
55vt65 sold for
£1,000 in a private sale - in perfect condition with 2x glasses and 3 years remaining guarantee)
So I would say somewhere between £610 and £1,000 - depending upon condition, glasses and guarantee - say £800?
(I really want to say lower as that much would be a struggle to justify for me personally but I am trying to be fair to you.)
Remember when you are comparing Ebay prices you pay at least 10% commission and another 3% to paypal so a £1,000 sales price corresponds to around £850 cash. Personally, having bought and sold TVs on the forums I would much rather sell on the forums as it is generally a much better experience for both buyers and sellers.
Ease of sale also depends upon where you are.
Please tell me that you are not to far from West Kent.