Congratulations.

We too didn't want to spend too much on the wedding as we were financing ourselves as well. Wanted a good Honeymoon which we got

We got married in the Conservitory in the Fitzroy Gardens..that took care of flowers and we only had 50 or so guests too and a few people who came to the ceremony and not the reception and they fitted in fine. We used a Celebrant.
Reception was finger food only, it was enough to fill everyone up.
You could see if you can hire a marquee and have spit roasts and extra's. They usally come up ok in price.
I have seen quite a few people do this in the gardens opposite the old Mercy Hospital. They have a rotunda and the caterers serve the the food and you can get a license and book a spot I think through Melb City Council. That way if you are getting married at the registry you can just wander over to the gardens to celebrate.
We also used a friend who had a hobby as a photographer and was great.
We had another friend do the video for us.
Pretty sure we came in around 2k for the it.
Another friend booked a local Indian restauraunt for her reception and it was beautiful and worked out ok in price too.