A few years ago when I was new at this game I asked about upgrades online as well as at check in, in the lounge and again onboard on a Economy Saver flight MAN-AUH.
Minimum bid online before flying was about £400, at check in that rose to £600, same in the lounge. When I eventually got onboard and enquired the price rocketed to £1200

no miles options available either.
More recently I asked when in the lounge at LHR and was again told the price in lounge was £1200 from Economy Saver to J... LHR-AUH. Again no miles options.