In some ERPs, it can be high.They insist on your hiring Specially Trained and Qualified Engineers to run their ERP.
However a good ERP would not insist on it and make your normal school passed employees also perform with ease.
A cloud based model works on SAAS (Software As A Service) basis. Here a monthly cost is charged on the basis of number of seats and the modules required. An On-site installation does not normally have a monthly charge. An Annual Maintenance Contract (AMC) is charged, which is approximately 20 % of the initial cost.