As Jeff says 55 to 08 reg maybe depending on spec etc at this price, another good source of information is the Hartech website, Barrie Hart has made an extensive study of the engines and their weaknesses, as Jeff says the IMS/RMS and bore scoring issues are often over reported, due to proliferation on the internet and some say that if you buy a Cayman with 80,000mls or more on it then it's past those problems others that when a clutch becomes necessary do IMS and RMS at the same time. I traded my MY07 Cayman S manual last summer with about 88,000mls on it the only problems in that time had been a blown chrono pack ( extremely rare and quite early on ) then gear change cables and coil packs at about 80,000. Servicing costs etc are close whichever engine but road tax differs dependant on which engine and when first registered, a 55 plate S is as cheap on tax as a 56 plate 2.7.
Manual is a good transmission, if it's not slick, check if it has a short shifter they are slightly heavier in use, if it doesn't feel lighter after a few miles it may have a cable problem, other problems can occur but are rare, Tiptronic is a rarer option, an automatic with override is a way of viewing it, not as good as the later PDK but some like it. It's good to have a good knowledge of what was available on the cars and to know which options you must have, may like or wish to avoid, the built in sat nav systems are not cheap to update...
Many of those who had 987.1's moved on to 987.2 or 981 as the Cayman whichever version is a great driving car, if possible try several or maybe a Boxster at a dealer to get the feel before taking the plunge.
Happy hunting.
