The prices will go down. There's already new manufacturing plants under construction all over the world so that the world doesn't have to rely on a single location of production. And the current factories have got their production running, it's only a matter of time until the extra demand has been fulfilled.
A pre-build rig can be as good as a DIY with a couple of caveats. First, the bigger the brand the more dedicated many components may be. CPU, RAM and GPU are generic and interchangeable. The motherboard connectors and the power supply may not be easily changed. Second, some manufacturers limit the brands and versions of upgradeable components through a whitelist coded in the BIOS. At least HP has been known not to allow video card upgrades higher than the next generation, and I've also seen some WiFi cards not being compatible with some HP laptops. It's really annoying to find it out the hard way when you get a new component and the computer refuses to boot!