There have generally been nice surfing/diving watches that are ~$100. Haven't worn one in like 10+ years tho, so maybe prices have gone up
Discussion
I use a shitty plastic Casio when I surf. Not gonna dive with it but it’s been great for like $15. You could probably get a nice gshock or similar for <$100 that’ll go deeper than you can. Maybe even some steel seikos for not much more
Actually I got a super cheap digital watch specifically for diving & it works great 😅