As already explained in other threads there was an influx of players recently without an influx of these items. Thus creating a larger demand, as well as people flipping in the ge which caused a price increase.
I never understood why people thought that high level items were gunna crash anyways tbh. No new items were being brought in and those items don't classify as "difficult too sell so they just sit in your bank"
yea i think jagex is starting to implement more gold sinks at this point as well as alot of money being removed from donations over this last month. hopefully they'll do something about changing drop rates to stablize prices.
A lot of variables and theorizing as to why this is happening, although I believe it's related to merching. Give it a few weeks to a month for prices to stabilize. I wouldn't buy/sell any significant items until then.