Wow! It's just a choice between one thing or another. I am sure if you have been into RC for a few years you know what you need to carry to avoid having to go home within 10 minutes of paying your race/practice fee.
Personally, I have 2 boosters and will pickup 2 batts just to be safe. It's not that I have money to burn, I just decided not to buy fast food for a week. I know my priorities......