If you have heaps of money and also want to enjoy your life, then pay a middle man ("bathroom renovator" or similar) to organise every thing for you. It can easily cost you more than 3-4 times. If you want to save some hard earned money then you can organise your own reno: buy your own vanity, toilet set, taps, bath tub (if need a new one) and tiles (tilers usually happy to pick them up from tile shops), then get few quotes from tilers with waterproffing licence and plumbers. Last step is to get new shower screen (we got it from Regency in Brisbane, including installation, cheaper then buying from Bunnings, also got a free mirror).
We just had a small bathroom (around 5 m2) renovated. A bathroom renovator wanted 15K (including new vanity, bathtub, toilet set, tiles and shower screen, excluding painting). I asked if I just get the shower done, how much he would charge. He said 11K. So I gave him a miss. Another bathroom renovator quoted 11K (I have to buy everything). So I went to Bunnings and bought a vanity, toilet set and taps and arranged a plumber to install it. I removed all the tiles from the wall and removed old shower screen, then arranged a tiler with waterproofing licence to do the shower (waterproofing and tiling). I also bought taps from Bunnings and installed them by myself. Of course I did the painting as well.
I paid plumber $500, tiler $2000 (including tiles), and shower screen $570 (including installation and mirror), vanity $300, taps $100, new toilet set $130, and some paint. You can see how much I saved.