If it has to be a Baron and not a Twin Catastrophy, Google up NAC Training at Lanseria. They used to have one, of one sort or another and as they will probably be the most expensive around, you'll have a base line.
You might want to check what the policy is with single yoke Barons for training purposes and also for the testing if you do not already have an SA rating on the aircraft.
A Twin Commanche at FAGC goes out at about R2,000 per hour. These days there is an additional charge for approach and landing fees.
Good luck.