Well the major early career Batman tech expenses are:
Batsuit (implied to mostly be a standard Kevlar bodysuit that is upgraded over the years.)
Batmobile. (The early designs were basically just armored cars with turbo engines)
Batcomputer: (The earliest version was a standard supercomputer that you could find on a IT college campus. Probably a few million at most)
Plus a few thousand dollars and some elbow grease to furnish the Batcave and you have a fully workable Batman ready to go.