Prices have rocketed due to simple supply and demand.
There has been a constant demand for parts and pieces to keep the huge fleet of civilian owned Lee Enfields going, either collectors, restorers or sportsmen.
The supply has not grown. Most nations that used the LE have sold them onto the surplus market by now. The only 'new' surplus rifles appearing on the market are ones that have been stashed away in locally held stores and come to the market in small numbers.
The days of the big dealers bringing in containers of Lee Enfields are gone.
Plus, there is a rekindled interest in military history. A lot of interest is brought on by video games and movies. A lot of new collectors want a WWI or WWII rifle like they see in video.
Increasing demand, shrinking supply.
You thinking that prices are high now? Lets revisit this in five years.
Popping primers? I would take a good look at your striker protrusion and the shape of the striker tip. The cause for pierced primers 9/10 times is here. Easy fix. 40thou protrusion and a nice hemisperical shaped tip.
O ring trick helps with fire forming cartridges segregated to that rifle for reloading. If piercing primers, the O ring trick wont help.