Praetor wrote:
MA suggests that there were 150 member planets in 2373 per 'First Contact,' so we can half the 600,000 to 300,000. Of course starbases and planetary facilities probably take out at least a third of that, but still. The potential for 200,000 ships...
Doesn't 10,000 to 15,000 seem so much better now?

I can now accept 10,000 to 15,000 ships, yes.
Does anyone know how many ship yards have been referenced in the various dedication plaques? 15,000 ships with a 100year service lifetime works out to an average of 150 ships constructed per year, or one ship per Federation member planet per year.
(edit) And if each ship takes an average of 10 years to construct, then there has to be 1,150 ships under construction at any moment in time. If the average ship yard has 50 drydocks, then that makes 23 yards...