If there is any one place NOT to cut corners, it is with paint.
2-part polys are so much more durable that they "pay for themselves" by lasting so much longer. They really aren't that much harder to work with and the prep is the same. A 1-part paint needs good surface prep just like a 2-part.
If I were you (and I will be next month as I re-paint my deck), I'd sand it down, coat it with Interlux primer, and then roll on 2-part Perfection. Interlux states that you can just roll on their white 2-part paints to give a satin finish. I've used the white 2-part before, using roll and tip, and I can attest that it self-levels very well. I'm planning on just rolling on white Perfection and not tipping it so that my decks will be semi-gloss/satin.
Any money you try to save today by not properly prepping the surface will be lost tomorrow when you have to repaint early.