It really depends on the startup, their traction, and your relationship with the founders. I've had folks ask for $10k-$20k for a seed round (the line between angel and seed is very blurry imho) with zero traction and a rough idea of the product market fit with a barely functioning MVP, and another team I spoke with wasn't talking to anyone without $100k to invest. Once you're past the seed stage, unless you're connected or an employee, it's $1MM+.

I focus on seed stage as I'm seeking high risk high return exposure for this part of my portfolio (and I'm not liquid enough to participate without investing in a fund for Series A on, unless I'm leveraging as part of a transaction).

(n=1, YMMV, accredited investor)