I'd peg most of them around 500 or so, actually.
Reed: INT and Science skills, fairly cheap. Bemdy tricks, not too bad. Huge gadget pool, pretty spendy. Toss in all the Contacts, Vechicles and the Base, and you're hitting over the 500 most likely.
Sue: Pretty basic power set, albiet huge levels of raw power on the force fields. I'd probably do a MP and an EC for her forcefield and maybe a smaller MP for her invisibility tricks. She'd probably fall a little under the 500.
Ben: Doable on 500. His physical stats are going to be impressive. Buying up CON and BDY are definately in concept for him, which puts him beyond your average starting Champions brick. I'd peg him at least 40 CON (he's the last man standing vs. the Champion, and his END is among the highest in the MU.), and at least 20, if not more, BDY. He's got good defenses, but not as high as a lot of other Marvel bricks, it's just that he can take a punch and keep on going. Beyond that, you've got some combat levels (i'd just give him some eight pointers), a solid skill set with decent mental stats, and some martial arts.
Johnny: Probably doable on 500, since he's not huge on stats, or skills. He's got mainly powers to suck up points, like Sue does. (Of course, they all have extensive contacts, favors and other perks to consider, like Reed does.)