If it's just the syringe that's bad, you can replace it with any plastic syringe that has a luer lock fitting (the threaded bit) on the tip, which is the standard for any needle or tubing connection, so you can find them easily online or sometimes at pharmacies or medical supply stores. For example, here's a 60 mL for $1.50 online. link 30 ml is probably a better size for brake bleeding, but anything in the 25-60 ml range will work.