2500 zen in local currency rate is I believe more than enough for one person's share of food, booze and accomodation in a BBQ + chalet outing.
While it may not last as long as a z-store ship purchase in terms of replay value, the BBQ and associated socialization gives many many good memories that come to you naturally. More fun if participants proceed to do a tailgate parteh or my favourite 3am convoys
Last weekend for 3000 zen I got on ebay an exquisite 19 inch tall Victorian doll that typically costs upwards of $250 USD when new (in today's prices, judging from similar costuming + accessories & miniature metalwork).
Given the pristine 10/10 condition, full supply of accessories, designer's certificates of authenticity and collector value, I could probably re-sell her for like 5x the price to certain collector's circles
High end dolls with realistic appearance are -very- hard to find and are not cheap, as this example from Madame Alexander would indicate.
So, for 3,000 zen that would be what I consider a deal of a lifetime
STF Flight Instructor since Early 2012. Newbies are the reason why STO lives and breathes today. Do not discriminate.
While I prefer to grind for Zen most of the time, because I only grind in ways I find entertaining (so it is not grinding, but a free reward to me), I find it very reasonable to buy Zen with actual money in some cases:
You want the Zen quickly, for example, to buy a ship that has just come out
You don't have that much free time to play, and thus want to enjoy that time you have the most
You prefer to earn fleet marks during the time you have, which at present is mutually exclusive with earning Dilithium, sort of.
You feel that PWE/Cryptic deserves some income in exchange for running and developing a great game.
Perfectly valid reasons.
That said, with 2500 zen I can buy 30% of a night's stay in a medium-priced hotel (which I have to do for occupational reasons frequently), or 25% of a week's fuel consumption for my car, of 5% of the monthly luxury of being a divorced father of a 11year old boy (who is awesome, by the way).