I stayed at the hotel Plettenberg Bay, it was lovely but as you say expensive. You may consider having dinner there though - they are part of the collection and have menu items at all their properties and the food is fabulous. Not cheap but not overly expensive either. Sorry dont know the other properties.

Missed Oudtshoorn on my last trip.

K&D booked one of my groups in the two hotels below - have you checked these out?. I can ask these people when they return how they liked it. They wanted very mid range priced hotels on the route.

Aug 7 Plettenberg Bay Bosavern Guest House B
Aug 8 Oudtshoorn Hlangana Lodge B

Worth looking at.