You cannot buy direct, you have to go through the partner channel, and ensure they are accredited.
The license cost is set by Microsoft, the reseller will add a margin and then the negotiations begin. Maintenance is compulsory year 1 and if you are buying now will be 16% of the software cost (non-discounted) from Microsoft. You will also want support from your partner which will be separate in cost, the maintenance is Microsofts. The partner will offer the implementation and training services. They will have a daily rate and depending upon your requirements this will be multiplied to a budgetary level for the project.