My brother and I have a small lawn mowing business. We have two 21' self-propelled mowers and we are going to get a bigger mower. We are looking for a used 36' or 48' mower. Do you think we should go big with the 48'? How much should a used 36'/48' cost? Also, should we try to get an Exmark or should we find an off brand? what's your opinion?