What's a nice business gift?

I’ve been away for a long time so I’ll start with a quick question: What would be a good gift to give to a male CPA who’d recently given you helpful financial advice? Something under $100, say.

Restaurant gift certificates are always good.

Find out what his hobbies are and give something relevant.

a baseball cap … with company logo embroidered on it. google it:
https://www.google.com/search?q=screen-print/embroider+any+logo+on+any+item

If you’ve seen his office, try to pick some smallish piece of art or decor that would match.

A nice pen. Even in this digital era, I still like having a few nice pens in my pen and pencil case. I’ll sign a bar tab with the Bic the staff gives me, but for anything else, I prefer a nice one.

IME, it is quite rare for most people to care about a pen. I use Pilot G2 gel pens. Give me an expensive pen (and I’ve been given a Montblanc, for Pete’s sake) and I am saddened by the complete waste of money. Harder to hold, write with and poorer quality writing result.

Very few people would recognize an expensive pen, fewer still would want one.

People like the OP need to think in the opposite direction. Stuff that a lot of people would use.

I’d suggest being very careful about gift certificates. OP doesn’t mention if the receipent is from a large firm or self-employed, or in between, but in many large finance and related area firms, Gift certificates are treated as cash, and accepting cash as a gift is generally a big no no, from an anti-bribery and corruption perspective.

Where I’ve worked, the rules about accepting cash extend to non-cash gifts, so you’re not allowed to accept a gift unless it’s of “nominal” value, typically under $25.