It depends where you get your scans done - all of mine are bulk billed except for the 20 weeks scan which costs about $170 and I get $85 back from medicare. There are other X ray clinics here that bulk bill everything and if I got my scans done at the hospital where I am giving birth then they would also bulk bill it all.

As long as I have signed the pathologists form, I have never been charged for blood tests or any pathology tests that I have needed done. I did forget to sign the pathology form for one of them and they sent me a bill in the mail (it was about $45) and I was reimbursed the whole lot by medicare. Alternatively, you can forward the bill onto medicare and they will send you a cheque made out to the pathology lab where your tests were done and you just take the cheque in to pay for it.

ETA: I did share care with my GP so I had to pay my GP bill (as per usual - so I was out of pocket about $30 per visit) until I switched to the midwifery care program run by the hospital. Instead of seeing my GP every 4 weeks and then every 2, I saw the midwives instead. This was also free. The birthing classes run by the public hospital were also free. I guess it just depends on your local hospital and GP. If you don't want to pay for scans, ask your GP if they can refer you to a bulk billing X-Ray clinic - mine has always asked me where I would like to go.