$5k doesn't seem ridiculous at all, and I think yiou could easily sell that watch if you decide you want something different. As a point of comparison, last year I paid about $5k for this OK-but-not-pristine 145.012-67, head only, and dropped another $1k into service. Figure I'd spend at least $500 for a service bracelet like you have, and your watch is $1,500 or more under the cost of mine. And I was pretty happy to get my watch -- from an auction at a small auction house -- for $5k.
FWIW, though, it looked to me like you got your watch through Catawiki, which might be the last place I would look. As another poster recommended, the Speedmaster101.com pages, published by a member here (
@Spacefruit) are an invaluable resource, especially the assessment and price guides. To the extent that I haven't been bamboozled in the vintage Speedmaster market, I owe it to a lot of time reading Speedmaster101 and the
Moonwatch Only book.