Logitech Z623 Desktop Speaker System – $89.99, Amazon
A good sound system can add a new level of immersion for not only gaming, but music and videos as well. Logitech's Z-series desktop speakers have long been one of the best sounding affordable options out there, and the THX-certified Z623 2.1 system will provide big, clear sound for just under $90.
For an all-out multi-channel setup the THX-certified Z906 5.1 system goes for $249.99 on Amazon.
Logitech G633 Artemis Gaming Headset – $149.99, Amazon
If you need a more private listening experience or prefer headphones to speakers (or if you prefer not waking the entire house during late-night gaming sessions), a high-quality headset such as the 7.1-channel Logitech G633 might just be the answer. The G633 features new drivers that can deliver equally well for stereo music and multi-channel gaming/movies, and it's compatible with PC and current consoles. Add a noise-cancelling mic and customizable RGB lighting and you have a quite a premium gaming experience.
The wireless G933 is also available for $50 more, at $199.99 on Amazon.
APC BR1000 UPS – $129.95, Amazon
If you've put any kind of money into your desktop system adding a UPS (Uninterruptible Power Supply) is crucial. The "pro" level UPS units from APC offer more than just power outage protection, with Automatic Voltage Regulation providing the system running on this UPS a consistent voltage – without dips or spikes – to allow your components to operate in a more ideal state. And while many less expensive options than the model above are available, it's also important to have enough power on tap to avoid overloading your UPS. This 1000 VA UPS provides 600 W of power for your system, which should be adequate for just about any single-GPU gaming PC.