Remember when making your decision to buy any bike is that is a toy for your enjoyment, so choosing the toy that is the most fun to you might be more important than choosing the bike that is the best deal in price. If you love 2 strokes, love what that reminds you of, and love being "that guy on the 250 two stroker", and really don't care that you are never going to be a paid pro motocrosser.... that could be a wise choice. If you have dreams of returning to Loretta Lynn's (even if it's just for fun to go back for week and race there) and need a bike that can get you there on the line in the top 42 riders in the country....... you might have to go the four stroke route. Sadly, the tracks, the competition, the ease of riding all come into play when racing at that level and the reason 99% of big bikes at Loretta's are 4 strokes is because they are easier to ride faster for longer periods of time than 2 strokes, and make the most power in a wide spread that makes racing easier. It can be done on a 2 stroke, no doubt, but it's just easier on a 4 stroke.
Weigh your real intentions with riding and racing for your life as you see it, and make the best decision for yourself. In a few years, you'll be able to have 2 bikes (or more) to race that appeal to different sides of yourself, but don't let your hobby slow your "real" life down until you are more settled in your life and career and can afford to satisfy both needs. You don't have to look to far on Pitracer.com to see many Vets that had one "race" bike in their 20's that they wrenched and raced with all they could muster at the time that have grown into a collection of various bikes now that they play on, ride on, and race on. As much as you love dirt bikes, you'll always be a guy that is looking for more bikes, you'll have more toys to satisfy all the things you couldn't afford when you were younger.