I found the definite answer guys. Here's how I did it: I went on https://www.steemnow.com/ and put in jesta as username. There you can see he has almost 100% voting power, and that his 100% upvote is worth $14.27. You also see his SP. if you divide his total SP by 14.27 you get around 2800SP. I tried with other steemers with a lot of SP and its around 2800-3000SP when their voting power is around 100%, so here it is folks.

The answer is : around 2800SP when you're at 100% voting power, as of today (this value will increase because payouts are still decreasing)