Hi, could you please advise?

The Lightning wallet that comes with this Primal app, what do you think is the BEST/cost effective way load it up with Sats?

There is a $ icon at top right of screen but it only gives me the option to buy $5.99 of Sats (through Apple Pay) I want to put about $300-$500 dollars of Sats on here and start buying things like coffee with it.

Thanks