There’s a thread on this from last year, early 2010 E63 wagon - had 6k miles from new last time it was for sale @ c. £30/32k?
I felt it was worth the money, other members chimed in saying it wasn’t etc. Turned out it had already sold for £30k just a few months prior.
I then contacted the previous selling garage who said It sold very quickly at the asking price and they had a lot of interest - took deposit over the phone and car collected/paid for soon after, and that they could have sold it several times over. I mentioned to them that my own car, an almost identical example with slightly higher mileage (14k I think at the time) but slightly higher spec (Designo paint/TV tuner etc) would be coming up for sale and they offered to buy it from me. I was looking out for a GL63 at the time and still had my E55K wagon so decided to let it go, for what I felt was a fair price for a straightforward cash sale, and made it more straightforward for me to move when the right GL came along.
Mine also went up for sale at £30k also and I believe sold for £28k in the end.
So they are worth that sort of money and there is a market out there for immaculate/low mileage/as new AMGs