Paid Upgrade Price Changes

Hello, forum newbie here!
I'm flying LHR-JFK-LHR in January seated in PE but have noticed the 'pay to upgrade' prices for UC have dropped significantly since I booked a few months ago.
The outward journey had dropped from around £1300 to £800 and the return leg has dropped from £800 to under £600.
I'm tempted to spring for one or the other I've never flown UC and likely never will again. I can afford it so why not?
My question is do you think the prices will fall any further or rise again as seat availability etc changes? How does Virgin's seat prices usually change over time like this?
Thanks in advance!
I'm flying LHR-JFK-LHR in January seated in PE but have noticed the 'pay to upgrade' prices for UC have dropped significantly since I booked a few months ago.
The outward journey had dropped from around £1300 to £800 and the return leg has dropped from £800 to under £600.
I'm tempted to spring for one or the other I've never flown UC and likely never will again. I can afford it so why not?
My question is do you think the prices will fall any further or rise again as seat availability etc changes? How does Virgin's seat prices usually change over time like this?
Thanks in advance!