I agree with
@watchyouwant that there is no use regretting this..
..But..
If like me you like to spend time overthinking and winning arguments in your mind that have been long closed then let's do an exercise, this is very high level and subject to variance depending on who looked at that local listing (are they someone who already owns spares, or an expert with a great spares network?), also, this is definitely not my area of knowledge, i just want to have a go at a valuation exercise and happy to stand corrected if anyone else feels like they want to provide their input:
Assumptions from my general knowledge (mostly gathered from this forum)
-Dial is 50% of the value
-Alpha hands are another 25%
-Pusher and crown maybe 5%
So the local listing was offering a 20% correct 2915 project at 5k (assuming case back, midcase, bezel and bracelet were correct).
Based on SM101 charts, assuming it was a 2915-3 (given non-steel bezel) we're talking about a watch whose value ranges between 18k if "poor condition" (btw if someone has a poor condition 2915-3 pls DM me) and 75k if "Excellent" condition.
Most likely the end result of a decades long search won't take you to owning an "Excellent" condition piece, let's say the upside could be 44k if you end up with a "very good "piece (at today's prices).
Therefore 5k was a good price, especially if you could get help from the experts in the forum retrieving the missing pieces, and especially if
a) You had 5k to throw in a project
b) You liked the idea of having to spend a lot of time, years for sure, retrieving the missing parts
c) A 2915 is in your bucket list (I'm sure 1 or 2 people out there don't have it)
And finally, to be perfectly honest with the OP, if i saw that listing in a local FB group i would also have doubts and most likely end up disregarding it, lots of effort required and I always have the feeling someone else has more knowledge and i won't be able to take the project to the point where i am satisfied with it and regret even spending money and time on it.
best regards
Duccio