Hi Chris, welcome to the Forum.
I bought a 2008 3.0si last year for 10.5K and it's presently on 65000 miles (bought it with 54K).
The price of the 2006 si is ok and the mileage wouldn't put me off. I intend to keep driving mine and at 12K a year it will rack up the miles - I'm going to keep getting it regularly serviced and the brakes suspension etc in top condition - I have a good independent that I trust.
Just make certain that you check all the usual things - see the post about checks to make when buying at the start of the E85 section on the Forum - that buyers guide is very useful. As these are capable sports cars make certain the brakes/discs are in good condition or take the cost to replace into account, similarly the tyres - most of us use non runflats to improve the ride and improve tramlining. Rears £130-140, fronts 100 110 to replace with Good Year Eagle F1s. The roof motor may need replacement eventually (or may have been replaced? £500 +)
These Zeds, given their performance have long service intervals and you may be surprised to find how little servicing has been done so I'd try for at least an oil service as part of the deal. If it's due an Inspection 2 service that is the most expensive one so check the service record.
The 3.0si seems to be commanding high prices for all years 06 - 08(09 reg) as they were the last of the E85 Zed and the most powerful 'normal' version unless you opt for the ///M (a different proposition and much higher running costs if doing high miles)
Take it for a good test run and check all the history and condition - you'll have to pay a great deal more for a lower mileage version - you should be able to tell if it's been a cherished Zed and then you'll have no hesitation in committing to the deal. They are a very special Zed.
Let us know how you get on
