Where do you get these figures from, Simon? The maximum price for 'a seat in the Gods' may be £64 for next Autumn's Beauty but there are many seats available at far lower prices.
A full view seat "in the Gods" to see Beauty can be bought for as little as £24. For Jewels the prices range from £9 to £55. For mixed bills these seats range from £6 to £36. Obviously prices are higher lower down in the House but it is only for Beauty and Nutcracker that the top price seats come to £100+.
I would add that, if you don't mind a very slightly restricted view, it's possible to see multiple performances for your £100+. Personally, I never pay more than £15 for a full evening ballet or £6 for a mixed bill.
Seats in the Gods/amphi for Manon, Swan Lake, Alice centre were £70, £64 is still very much in the £70 region, this is what's now considered a "good" seat. At that height, that far from the stage I would call that a cheap seat. Once you get down into stalls or grand tier, to sit in a restricted view is upwards of £60, for one of the best seats for a three acter you are are looking at £100+. Yes, indeed mixed bills are cheaper, that's why there are fewer of them, you will never sit in front, centre stalls, grand tier for £36. The only time that ever happened in recent history is for McGregor's first mainstage commission.
To claim that the cheaper seats in the amphi, slips or restricted are approaching a great or uncluttered view of the stage or even affords a full view simply isn't true. The sight lines in the ROH are notoriously poor when compared to other great lyric theatres around the world. If you like those cheap seats that's great, they do my head in, not least because I paid what I considered a very large amount, £70 for what I consider a very mediocre seat for Alice.
Moreover, the prices for the next booking seasons have yet to be released, but given the 15% cut in public funding to the ROH the place this will immediately impact is in seat price throughout the theatre.
I don't agree though that the £10 three act and £6 mixed bill slip seats are worth buying, nor the standing restricted view seats.