Always a dilemma. I was worried that I would regret selling a nice featherweight field grade LC Smith. I sold it. And now I have a much nicer WW Greener that I bought for less than I sold the LC for. It is amazing what you can find when you suddenly become fixated on finding a new gun.
Don't forget too, if you're younger and it is not the gun of your dreams or does not hold sentimental value, there will be many other opportunities in the form of other guns. You could always sell it for $2500 and spend a grand on another shooter as well, applying the balance to your fund needing situation.