That's actually a reasonable price to replace the rack. Depending on how severe the leaks is, you can probably keep refilling the reservoir for a long time. However, if it ever runs out of fluid completely, you'll be looking at a new rack AND a new pump. Oh, plus you won't have power steering. It'll be hard to drive home from where ever you are when it bites the dust
I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology.