When I worked next door to the stadium lot, it was $3 for employees parking, $5 general public; (my son worked at Boog's BBQ). So I checked the price:
https://stadiumparkingguides.com/camden-yards-parking/
Looks like $15, if this is up to date. Still very outrageous, IMO. But at least it's not $30 yet.
Heck, the $5 was considered a rip-off back then. The lot was only about 10% occupied most evening games. (This is the lot under 395.)
I no longer work in Balto, and don't miss it.