$600 is more than I would have spent on it to get it this far. However I will spend more on a bike project than many others would think wise. Many times the valuations people offer on these posts are based on what each individual would pay. Some people want to fix up an old bike to enjoy and some want to get it ridable and try to flip it for a profit.
But to answer the root question you asked, it is worth what you want to spend on it if it makes you happy.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke