I would prioritize the performances (needing buses) in YOUR priority and depending on whether your stadium is on campus or a bus ride away may change some of these).
Pre UIL marching
All other home games
1 Additional Marching contest
Concert & SR
Pre Concert & SR
Solo and Ensemble
Recruiting performances at the elementary
Community performances, (might have to start getting paid for these to cover the cost of fuel)
Away football games
This is not a full list, just the quick list I could throw together. And you can't tell the Admin you won't go to away games and then go to 5 marching contests. There has to be some reasonable level of compromise if the budget is really an issue. Once you calculate the cost of those trips compared to your budget now you can have a professional and reasonable conversation with your admin and if the money ins't there it isn't there. You simply have to do your curriculum first and unless they are giving you additional money, you can't physically do everything they want. I have yet to find an admin if I spelled it out, especially with dollars, that they wouldn't understand, accept no, or find more ways to pay for things. There is only so much money. Lastly, you have to commit your entire budget in this presentation. Lay out every single penny you are spending to show them. You can't just walk in and say there isn't any money while you then follow up telling the district they are paying 2k for you to go to TMEA/TBA and you still expect new instruments and a couple thousand on reeds for the kids. Be smart, thorough, and incredibly detailed to the penny!