I also live in Melbourne and the number 70 stops right outside more door, plus have a small car so size of pram/stroller very important. I chose just to use slings with my DD, now six weeks and the plan is to get a pram/stroller when she is three months, Maclaren do one which is suitable for from 3 months but is 1.5kg lighter than the new born ones and looks to be a reasonable size to get on trams occasionally.

Here is a link to a thread I started about prams on trams

http://forums.bellybelly.com.au/foru...melbourne.html

So we are getting on ok with just the slings and will be fine till three months, the only issue I have really is if out at cafe etc is more difficult to eat and crumbs tend to drop on the baby!