One of the primary functions of a reviewer is to help make sure that the finite resources society has for research are used wisely. It is consistent with that role to be concerned about the budget for this proposal. At the same time, the criteria you are given make no reference (direct or indirect) to budgetary considerations. Therefore, you cannot take the budget into account when rating the proposal. You can, however, convey your budget concerns directly to the person who asked you to review the proposal. In some cases, budgets are negotiated after the decision has been made to fund the project.