Owner builder, is it worth it?

I'm currently researching the best (and cheapest) way to build a house. My plan is to buy a few acres in rural vic (probably Pyrenees Shire) and build a small 3 bed, 1 bathroom, open plan living/dining/kitchen. Guessing it will be around 100m2. I could go kit home but I don't really like any of the plans plus the costs don't include all the expensive stuff. Atm I'm thinking prefab frame and roof on concrete slab, maybe use a builder til lock up. I myself have basically no idea how to owner build but my dad has done it in the past (20 yrs ago), he also just renovated his house which include painting, tiling, laying lino, rendering and making cabinets. So my dad basically has all the skills needed, he also has a few friends that he uses for plumbing and electrical stuff at his place, and he is willing to help me. He is currently think using containers would be the cheapest option. I honestly have no idea how much anything will cost and have been searching the net trying to find some ballpark figures but thought it might just be easier to ask on here. Can anyone give me some basic figures? Or some ways to get a good house for less money? Is using recycled/second hand materials worth it? im thinking of doing this build in stages, so build a basic house first with basic fittings, windows, kitchen and bathroom then upgrade/extend in the future when I have the money. Is there anything I should consider to make extending in the future easier? This is all just a bit of a dream atm and won't be happening any time soon but still I would like to know how much money I might need and also what reading/research I should focus on. So any suggestion and advice welcome. Thank you.

Only you can decide That?
Start with a sketch and then weigh up the options based on data, quants & Costs,etc
Goodluck

The idea of OB to save is appealing but given that you are a novice you are way behind the starting line.
Don't count on friends and favours because it all has to be repaid and it could be more than you got.
Any potential savings can be quickly eroded by blunders and you could end up with over priced sub standard home+ huge loss of your productive time that you could have used to increase your income and get a bigger loan.
I-recommend you get some proper education in building + work for a builder for experience before attempting OB
Don't forget even professional builders can blunder.