Summer, I had an u/s done about 2 years ago to check everything over with regards to TTC, and mine cost about $270. Cannot remember what I got back from medicare though. This would be at the high end of the scale, considering the people I go to are the only ones around for thousands of klms.
I 've had to have many u/s while growing up, not unusual for me to have at least 2 a year, and they all ranged in different prices depending on what was being done.
Maybe ring the place where you are having the u/s done and ask them the price and if that is with the medicare rebate included or do you claim it afterwards.

Nic