Not sure where abouts you are, but I have gone down to canberra for a short trip away by myself. Last year I went to Floriade - ok, so I did take the youngest child, but we went for two nights and it cost $150 per night for a motel and we went shopping, did floriade and also did a walk around the lake. There are so many options in Canberra - museums, art gallery, shopping, or you could do something like the glassworks and make your own glass bauble etc. Decide where you want to go and then have a look on wotif, gostay or lastminute for accommodation. Or you could find out what things are on - maybe a show or a concert and base your trip around that.