It's called a Barrel. You can get as many 3ml and 5ml barrels as you want for free from needle exchanges. Walk in and walk out.
Or if needle exchanges aren't your thing just ask for a 3ml syringe without a fit from the pharmacy. If you give a shit what other people think about you, tell the lady behind the counter you need it to refill inkjet cartridges or some shit. Alternatively you can swipe em by the handfull easy enough in any hospital, but that's illegal and immoral beh.