Any 993 is an old car by now, and more importantly it is an old sports car, which in it`s time through the hands of how many owners(!!!) may have occasionally experienced a bounce of the rev limiter, and a bit of rough treatment from an owner who knew at the time of purchase that they were not likely to hold on to it as a keeper..?
Garage queens might fare not a lot better on their rare runs in the sun, though they should at least shine in the sunlight even if the conditions in the garage encourage the chassis box sections to rot from the inside out. and just think of those poor valve springs lying for month after month fully compressed, the valve lying opened it`s face and seat perhaps becoming contaminated in the damp air, the bores too, but that may clean up once fired up, well at least to some degree...? What about the time it takes to build oil pressure on the first start of an engine which was garaged while hot and left for months giving the oil time enough to drain out of very important places... ever heard a laid up engine rattle on start up....perhaps causing things to wear a tad, when regular runs might have incurred less wear..? Laying up an already old car is unlikely to determine it will improve with age...? But if the desire or need is related to investment potential.... good luck with that now..?
£60k air cooled Porsches as one might expect to pay for a good one that has had EVERYTHING gone over with a fine tooth comb, may be worth their beans for someone who wishes to use the car as intended by it`s designers, but then I suspect £30k may easily be spent on a 993 to bring it back to anything like it`s original quality and performance, were that a desire, and given all will have circa 100k miles on the clock, IF one believes whatever the clock displays and paperwork is produced as proof... chances are it may shine like a new pin, however what lies below that coat of paint is not always of...err..Porsche quality, I suspect there are many patchwork Porsches out there and with 100k on the clock may be in line for a top end overhaul any time soon. If you want an oil tight 964 or 993, perhaps best factor in another few bob, how much might it be to replace on original exhaust which is now how many years old...The suspension is a tad complex too compared to all earlier 911s and which also require a bit of expensive attention..?
Sure there will be a few air cooled Porsches around that have found careful owners at some time in the life of the car and owners who have over capitalised in their restoration processes relative to the current and future market value. There will also those who bought into the idea of investment and may not have not spent a bean and may now be looking to cash up..?
Thus unless one has perhaps £10k spare in the back pocket for contingencies, a £30k 993 or 964 seem to be a bit of a risky bet to escape from should the need to re-capitalise become a requirement or desire. Some Porsches like houses these days can find themselves hard to shift and their owners imagined valuation... and if they are slow/non movers it seems even the dealers are giving them a wide berth..?
Spare parts were ever ridiculously priced to the extent that mud hut manufacturers got in on the game which seems less than ideal, also the cost of parts after Brexit... who knows...? Not I.
I wish you the best of luck in your search for a car that fits your needs.... Who said value is 10% and desire is the other 90% of the price paid...???