Hi Jay - tricky one as I'd never even considered this!
Parts (quality vintage movement, parts to service and repair plus a new case being the most expensive) probably just north of £100 on this watch ... but what then for labour?. For me it's effectively free so I have something bespoke and unique at a pretty reasonable cost ... but what would you charge someone else for all that labour? I guess pick a per-hour figure you think is reasonable for 'skilled-but-amateur' work and assume about a man working week at circa 40 hours to complete (I made this watch over a period of time for fun so didn't clock time I'd spent on it but this feels about right).
If you consider that just the professional service on one of the big brand watches is circa £700 (something that can be done in a day) then maybe what price you come up with doesn't seem so bad in comparison ... but of course it is still amateur work!
If you had money to burn you could engage a professional watchmaker e.g.
http://www.strutherswatchmakers.co.uk/bespoke, who for a minimum of £30,000 will design and build whatever you like!