Cool vintage look to those. Nice catch!
You can get rechargable 9V batteries for that, which will save you money in the long run, if you plan to use it a lot. [I use rechargables for my metal detectors that use those batteries --most do!] Otherwise, you can also use six smaller 1.5 volt batteries, wired up appropriately. In total, they get bulkier, of course, but electrically it's an option.