Like what? 2100 K is almost a minimum as far as I'm concerned (750 words ~ two minutes * 28 entries) and if you've gotten that far... hell, might as well go as long as you feel like.
Something like 16 - 18 Thousand. On one hand, you don't want people going completely overboard, but you also want a level playing field.
Or 20+, because I'm being unreasonable.