Of the cheapies that actually feel like legitimate playable characters, i'd put your bets on Crazy Catastrophe, Rare Akuma, and Chuck Norris. They're outclassed, sure, but they don't give the opponent a heart attack just for existing in the same roster.

Of course, your mileage may vary and you won't live the Dragon-Tiers down, but Dragon-tier cheapies are not in circulation for obvious reasons.