I am in the same position at the moment, I think the big question is how much will it devalue the car? If its more than the cost saving then you have to weigh up if it's worth doing.
Personally I really enjoy working on my cars I know what I can do and I know my limits, however the bit that adds value ie.. A stamp is for the simplest task, an oil change!!!!
This really frustrates me I have purchased cars in the past with a FSH all that had been done was it had been taken to a dealer had an oil change and stamped, loads of advisories but no further receipts.
The other question is how long you plan to keep it, if it's short term then you need to preserve as much value as possible so a service and a stamp is probably worth doing.
If you are going to keep it for a long time I can't see how it will make a huge difference, keep all the bills and receipts and when you carry out a service or any other repair, type it all out and print off a "invoice" to yourself to keep a record of whats been done.
I bought a Ferrari 308 off a guy who had done exactly this for the last service and cambelt after speaking t him and seeing the history including his own work. Was happy that it had been maintained well.