It appears that the 'seller' isn't particularly motivated to do a deal, but I can offer some sort of advice on the faults you list:-
morciii wrote:the rubber lip under the bumper was falling apart, battered and torn.
simple to replace (about £15 inc P&P) - but what other damage may it hide to the front underside?
morciii wrote:the brake discs were completely rusted
New front discs can be got for about £25 delivered - not uncommon to find them rusted if the car has been standing for a while, but it suggests that the whole brake system may need some maintenance.
morciii wrote:the indicators and lights on the bumper were cracked
I've got a spare pair of OE lenses (so, just the cost of postage to you!) - clear ones are also available (which is why I've got a spare pair!) for about £70
morciii wrote:the window seals were missing on the drivers side
If you mean the horizontal rubber strip between the window and the door, they are available from PNM engineering for about £70 a pair (or they can be modified yourself from a 'standard' profile bit - there are instructions availlable.
If you mean the spongy 'A' pillar seals, then see below answer.
morciii wrote:all roof seals were needing replaced
Complete sets of OE roof seals are sometimes available as a set, or some can be bought seperately, however, Jamie-N in Scotland has adapted EPDM rubber seals to replace ALL roof 'A' pillar and door seals - instructions are on the forum, or he will sell you a complete set (or whatever you need).
morciii wrote:the lock for the boot had broken off and was in the drivers side pocket
Again, not uncommon - it's only held in by a metal 'U' clip which can come off - the mechanism is seperate (I've got a boot lock somewhere round here....)
morciii wrote:and the engine showed signs of leaking oil
It all depends where from - there are some 'common' leaks which can be repaired cheaply (or even free) - the CAS 'O' ring and blanking plate 'O' ring are the usual ones and will show up as a drip down onto the clutch bell housing which spreads arround and looks worse than it is.... Then there is the possibility of a leaking cam cover gasket (easy to change, or seal with silicone), anything else will depend on where it's leaking from...
My main concern is that he is advertising as 'Service History' when it's clearly only a partial history - so it must be assumed that (at best) the oil has been changed. Unless there is clear evidence to the contrary, budget for at least a cambelt change (along with associated tensioners/water pump).