Infrastructure costs depend upon whether you want an On-Premise installation of SAP or you wish to have SAP installed On-Cloud.
On-Premise installations have a number of hidden costs, e.g. costs of personnel to manage the infrastructure, obsolescence costs, power and back-up costs, etc.
On-Cloud costs, on the other hand, are a fixed cost per month to a very large degree with a negligible variation. Typically, for SAP Business on SAP HANA, this could vary from $30 to $40 per user per month for a 24 x 7 available infrastructure with many advanced features that are impossible for an SME to implement On-Premise.
More and more customers are opting for On-Cloud infrastructure with state-of-the-art environments at AWS, Azure & Google; all of which are certified by SAP to host their solutions.