I wouldn't go in with the idea of reselling and I certainly wouldn't let that question dictate the number of points, UY or anything else. My suggestion would be to determine how many points you likely need per year if you're fairly successful. If that's under 150, I'd up it to 150-170 but for larger numbers I'd suggest underbuying by maybe 10-20% for most situations. Looking at 2 extremes say one is looking at a studio adventure season for a week, that puts your needs at around 100-120 but there's no wiggle room other than shorter stays or less frequent stays. And if
DVC reallocates against you, it could put a big damper on plans. As compared to say a 2 BR during magic or premier where you have far less risk and far more flexibility. In that situation one might have a "need" of 350 but maybe go for 250-300 OR take a different route such as buying even less, maybe 200 and then planning an add on later (? at a higher demand resort) once they have more info.