Hi Phil,
I'm a newbie as well and just bought a 03 z4 and loving it. Just want to pass on my little experience of my reason journey of finding and purchasing a z4. Firstly you are in the right place for any advice, been on here less than a week and found it very helpful and responsivie, wish I had known about the forum when I was at your stage.
So my advice, if your buying a Z with full service history ( which will add to value) make sure you check through it well with dates and signitures with the dealer stamp and as much paper work of work done as possible. Check all the door locks work with the key and preferable one that has had the roof motor mod done ( replace to the boot). Check little things like the door mirrors working. I think, because ( if your getting a soft top) of the soft top the doors will not seal quite as well as a coupe and if the car has not spent all its life in a garage there will be a little water ingress which think may not help the locks etc.
Maybe the autumn will be a better time, when you find one give it a good road test if you can, don't like me, be dazzled by the beauty of the car and the pure excitement of finding the right car and let your guard down.
Ps and ask lots of questions on here and if you know someone who has a Z take them with you to look at the car
