Federal agencies scrutinize requests for professional support staff and such charges are strictly audited for time and effort reporting. Check the current rates for student employment. As with other university employment, wages are based on job responsibilities. Externally funded wages must be similar to those paid from internal funds for similar work. When an agency specifies a rate for a research assistantship or other stipend that exceeds the institutional pay scale, the agency's funding policy will apply.
More expensive items are to be listed as equipment.
All federally funded airfare must be on U.S. flag carriers unless using such carriers results in federally defined delays compared with a non-U.S. carrier OR no U.S. carrier serves a particular segment of the trip. Travel also includes meals and lodging, or per diem. Federal agencies expect a figure in line with their own rates. Think through the items you will need and quantify them. This shows the reviewer you have given thought to how you will spend money and also protects you from surprises.