Buy a prebuilt PC
Best Buy's website offers around 100 new Windows 7 desktops and all-in-ones. Newegg and Amazon each have hundreds. Individual PC builders also sell Windows 7 PCs. The phasing-out of consumer Windows 7 PCs means they're already often priced somewhat higher than comparable Windows 8 machines, though.
In fact, many Windows 7 PCs available today already stick to the Professional version, which is helping to drive Windows 7 PC prices higher: Virtually all Windows 7 computers sold directly by Dell, Lenovo, HP, and other mainstream PC makers reside in the business category. Boutique PC builders, such as Origin and Falcon Northwest, also offer Windows 7 as an option for their built-to-order rigs.
Roll your own PC
Now, the good news: E-tailers apparently stockpiled Windows 7 licenses by the bucketful before Microsoft cut off access. Finding boxed copies of Windows 7 online is dead simple. Even better, Windows 7 Home Premium still sells for its recommended $100 MSRP. Unlike hardware pre-stuffed with Windows 7, there's been no price inflation on the software front.
Considering that you can still find boxed copies of Windows XP online, expect to see Windows 7 on sale for awhile, though its cost is sure to creep up as availability dwindles over time. Just be sure to confirm what you're buying. Some third-party sellers offer "open box" copies of Microsoft's operating system. Steer clear of those.
Downgrade Windows 8 Pro
If you've already purchased or built a Windows 8 Pro computer and found you loathe Live Tiles, all is not lost. Microsoft's rarely invoked downgrade rights can be tapped to transmogrify your PC into a Windows 7 Professional system.
You'll need to have Windows 8 Pro installed, and your PC must have run on Windows 8 Pro from the get-go—basic Windows 8 installations upgraded to Windows 8 Pro after the fact don't get downgrade rights. You'll also need a product key and an installation disc for Windows 7, which Microsoft and most PC makers will not help with.
Nevertheless, downgrading has its upsides over simply nuking Windows 8 and installing a fresh copy of Windows 7. Namely, you can upgrade back to Windows 8 at no cost if you change your mind in the future.