I'm in a similar predicament myself, had the car for 7 years, bought it when it was 3 years old with 7k miles on the clock & serviced religiously at supplying VW dealer since new.
I've just booked it in again for a major service, 4k miles since last service 12 months ago. I also get the cambelt done by VW & ask them to change the waterpump every time - It's had 2 cambelt changes in my ownership.
VW have menu pricing for service & service related work for all VW's between 3-10 years old & this year they applied that to my car even though it was over 10 years old. Minor service is about £130 & major service about £260. Cam belt change iirc is about £340.
To be honest, I rang around a couple of VW specialists & the difference in price was negligible, so I opted (rightly or wrongly...) to carry on having it serviced at VW & get the stamp in the book. I don't know if it will add any value when I come to sell but thats the choice you make...
If your car has got a full VW service history from the supplying dealer, I would imagine its very much like mine in that it has been well looked after. Chances are that you might not end up with an unexpected bill, but I guess that depends on the dealership...