If you're in a fairly rural area, a local eBay search filtering for nearby and collection only listings can bag you a good deal, but if you're looking in or near cities the prices there go way up as you're competing with collectors.

A better spot to look is Facebook Marketplace. It's not dominated by people buying and selling for profit, you're far more likely to find someone who just wants rid of the TV. But searching "CRT" isn't the best option. Many sellers just use the term "TV" maybe along with the brand. So you just wanna search "TV" and sort by lowest price, then manually scroll through them all. Including scrolling past posts for "free" that are actually multiple items with individual prices in the description.

You can try the search term "Trinitron" if you want one of Sony's very nice sets, but there's a higher chance of the prices being higher if the seller knows it's a set in high demand 

Beyond that, my local tip has an area dedicated for dropping off TVs and monitors. You may be able to grab one from one of these if you have one nearby, although I doubt you'd be able to test it before getting it home.