I have been doing this for a few months, the success rate is not 100%, but might worth a try if you are interested in saving money and most importantly - can wait patiently :-)
I first saw this Yates Plant Cutting Powder in Bunnings and thought might be a good idea.
It's very simple, just follow the instructions and keep watering it for first few weeks and most of time it should have roots and starts growing. I think it also depends on the type of plant, which season, which part of the plant did you cut, ...etc, also heard that better avoid flowering season and pick the time which is not too hot/cold. You might have to experiment it a bit to work out the best way for different plants.
The photo below is the most recent one I did last week. The one on lower right hand side was the previous one a few weeks back (or months? can't remember...). Yes, I am a bit lazy/greedy and tend to squeeze too many of them into one pot...
And of course, you need to find at least a full grown plant to cut first... Will leave it to you to work that part out :-)