89 tire caps

If all else fails your budget, there's always bat-caps.

You want to do a, "Batman Forever" theme? Use glowing green PLA
You like the theme, "Batman & Robin"? Use glowing blue PLA
Lego Batman? Use Black, or a really, REALLY dark grey PLA.
Adam and Burt 1966 Batman? Yellow with black accenting to make people say, "Holy Rollers Batman!"
Going beyond with Terry McGuiness theme? Use glowing red PLA with black accenting.