I realise this is several months late, but you can get a "Good Morning" ticket for Jungfraujoch here:https://www.jungfrau.ch/shop/en/good-morning-ticket-jungfraujoch
It offers you a 30% discount on tickets, on the condition that you need to catch either of the first two trains up the mountain (leaving Kleine Scheidegg at 8am or 8:30am) and then descend on or before the 13:13pm train.
We did this a couple of months ago and it was great - catching the first train up means that you can get out on the viewing platform before anyone else and take some great photos (or video, in our case). It also gives you enough time to go through all of the "attractions" up there, hike over to the hut across the glacier etc, then return down the mountain for lunch in Grindelweld. It's still not "cheap" I guess, and is still comfortably the most expensive World Heritage site we've visited to date, but "it's not cheap" is probably the most apt three words to describe Switzerland :)