You need to do mirroring at the disk level, not the database level. The number of databases is then irrelevent, it's only the total volume of changes that is an issue. A good mirroring system will support a lag time when things are very busy and/or the channel to feed data to the mirror is slow/busy.

Trying to recover 500 separate databases using log shipping would be quite a task, even if automated. Make sure you can accept the length of time it would take you get 500 databases back up and running before choosing that solution.