A top pick budget alternative to AirPods are $20 right now (Update: Expired)
The Anker Soundcore Liberty Air wireless earbuds sound as good or better than Apple AirPods, and they've never been cheaper.
Anker's Soundcore Liberty Air earbuds are a solid alternative to AirPods at $50 -- which is less than half the price of Apple's signature wireless headphones. You don't have to pay even close to that, however, that since the highly rated true wireless headphones are currently down to $20 on Newegg.
This the lowest these quality buds have dropped; we normally see them priced around $60 or more. Although, Amazon has the white model down to $25 right now if you prefer those.
It's worth noting that these are a former CNET top pick for budget AirPod alternative, but they're now more than two years old. There are newer, cheap options worth considering but it's not likely you'll find ones as cheap as these.
In his review of Anker's Soundcore Liberty Air, David Carnoy explains how these 'buds "sound as good or better than AirPods" with "solid wireless performance, five hours of battery life and come with a compact charging case that delivers an extra three charges." The big difference is AirPods will run you at least $130, while these can be had for a cool $20 right now.
Even if you've got a pair of go-to headphones you love, it's handy to have a backup pair for emergencies that actually sound good, and this is about as inexpensive as you'll find.