This was the pricing for Brussels to Beijing (9hr flight) last week:

Econ first row or exit row: 135 euros
Y/B/H/K/L/M to business class 700 euro
Other cheaper fare classes: 850 euro

A woman was aggressively marketing the offer to people in line at check-in. Then again at the gate. She even offered me a special 2 for the price of 1 for the exit row (we were practically the last to board). I was in a row with the middle seat open so there wasn't much point. I would have paid 400 for business, but not 850.

They also made an announcement on board that upgrades were possible. Didn't ask the pricing then.

An agent told me pricing was in the 400-600 range last year for upgrades to business.