If you want a "standard" device, the Samsung Button is not a bad choice. Some people have reported problems with duplicate events after it's been dormant for a while, but Samsung also claims to have fixed that with recent firmware updates (though if you have an old one, you'll unfortunately need a SmartThings hub to update it). The only thing cheaper is probably Xiaomi, which aren't standard and can be a bit flaky unless they're close to the hub or (close to and paired through, it seems) a known-compatible repeater.
I might also recommend this thread, which details the capabilities of every button device natively compatible with Hubitat. You're likely to see some you've never heard of and might be worth checking out: Hubitat Elevation supported button controller capabilities matrix
