I bought a cheap one from China to try it out, similar to ebay.com link: 1set High Frequency Response DTL TTL and CMOS LOGIC PROBE LP 1 and it's worked well enough I've never bothered to get a better one.

Although not useful as often as a logic probe, I also picked up a cheap logic analyzer, which basically lets you record multiple signals and view them on your computer. For quick board inspection the logic probe is much more convenient, but when you need to know anything beyond 'is this line high, low, or pulsing' (such as whether two sides of an inverter are inverting, or what speed the clock is going) it's really useful.

For $20-30 for both you can't go wrong.

If you like to "build-it-yourself", here is a good kit version:

ebay.com link: Elenco LP 525K Digital Logic Probe DIY KIT requires soldering assembly

I bought one of these a couple years ago and it worked pretty well for the board repair I did.

https://www.amazon.com/Elenco-Electronics-LP-560-Logic-Probe/dp/B000Z9HAP4/ref=sr_1_3

Elenco LP 560 is what I've used for years. Think I spent like ~$15 on Amazon. Probably saved me several grand in board replacements.