Hello Surry,
Forgot to mention that you can also prepare your budget amounts in Excel and simply upload them to AX. Even though your customer probably does not want to budget on each and every financial dimension this might be a quick way allocating Budget amounts over different financial dimensions and getting Budget values into AX.
Hope it helps,
Ludwig
Please see: www.dynamics101.com/.../budget-register-entry-upload-excel-add-in-for-microsoft-dynamics-ax