Pit and Ike are the cheapest, though there are counters for each but you have to be good at the type of character that can counter them, many characters just can't.

So far Peach for me...

Ike is generally a pushover if your character has decent reach or a medium-long ranged projecticle attack.

 Melee Peach maybe but I'm a Peach user and I really have to work hard to get my kills with her. She doesn't have any low percentage kill moves and her jumps aren't very high (thank God for her float ability!!). She's good but cheap she is not!

I miss the Melee Peach, she seemed a lot tougher in most respects however...  I'm glad they strengthed her Side + B and regular A (seems like it has longer reach too).  The Side + B used to be nearly useless.

I never used Peach's side-B in Melee, it's good now but you gotta be careful with distance cause if you fall short you're in big trouble. What I miss most from Melee tho is her second jump height and her godly Down-Smash.

True enough.  Seeing the down-smash was like seeing Sheik's air chop.  I was like "Nooooo where'd the power go!?"  ^_^

 That move sucked people in better than a vacuum in Melee!