Your figures are completely off. Clexane costs in the region of $8-10 an injection. Different prices in different areas but nowhere near what you are quoting
http://www.pbs.gov.au/medicine/item/5434B-5435C-8262W-8263X-8264Y-8510X-8558K-8639Q-8640R-8716R-9195Y-9196B