Miners den had a minelab day special where the 4500 was $3300, call Bendigo office and see if they will still do that price for you, I asked for the same deal a week after it finished and they did the same deal. You may be pushing it now as a few weeks have passed, but worth a try.
Just pull a sob story and say you didn't have the funds at the time, and all your mates got one at the good rate.