Have you tried SpotHero? That's where I usually look when I need occasional daily parking. If nothing else it can be useful for finding garages.
https://spothero.com/washington-dc/courthouse-metro-station-parking
(I would be a little careful about their rates because one time I paid and when I got to the garage found out it would've been cheaper to pay the garage directly - SH had charged a "guaranteed reservation fee" of $1 to "hold a spot" and the garage was half-empty so it wasn't worth it! That was a rarity, though. Usually it is cheaper to buy the parking pass through them rather than the garage.)