First of all, thanks for having a dragon hangar sale, I needed it since my dragon hangar was overflowing I bought 60 spots (240 → 300) and my rune count absolutely died from it. Going from 70k to 35k was quite painful to watch be spent. I’ve read the wiki and it says the price of hangar slots maxes out at 10k which is good but still feels too expensive even with a sale making it 7.5k runes. If I were to buy the rest of the slots to 420 at the normal price, it would cost a whopping 120k runes for 120 slots. The discounted version would still be 90k which is still quite expensive. (12x7500=90k) vs (12x10000=120k).
My proposal is to make it so that those who are struggling with runes can use polished amber as an alternative option to upgrade it. Either that or to make hangar sales have better discount sales such as 50% off. I hope the RoB team sees this suggestion and considers adding it in, because I know many other people are always nervous and constantly dealing with a filled Berk.