Air China business class bidding at ticket counter or gate?

Hi community, planning to travel to China in a month or so for personal trip from Washington Dulles IAD to Beijing PEK. Air China is the only airline that has direct flights, economy class tickets are about $1600 and business class about $6500 roundtrip right now. I took this flight last year and remembered that either at the ticket counter or the gate the airline was offering some price (hopefully discounted and cheaper than if I were to buy it now, can't recall) for business class upgrade.

Traveling with elderly and would be really nice if we could get a business class ticket but paying $6500 would be painful. Anyone traveled with Air China recently remember whether the last minute bidding for business class upgrade was a better deal?

Thanks for your input.