Have a look at http://www.waterfront.co.za/live/hotels.php The City Lodge is probably the cheapest, I guess around $40-50 maybe cheaper. The Breakwater Lodge is nice but it is not always easy to find a room there - very popular.

There is quite a few hotels around the Waterfront area, quite safe and full of tourists.

From the Waterfront daytrips are easy to the surrounding areas and winelands.

Regards

Joshua