Hi to give you a rough idea on the costs:
1. My custom 42cm cube tank 8mm glass, with cabinet, sump and pumping cost me around 700. For your size, I foresee will cost at least a thousand dollars.
2. Skimmer will cost at around 150 and above. I will recommend Bubble Magus for its lower cost.
3. A return pump, if going for eheim universal pump will cost at least $200. Jebao will be cheaper.
4. Live rocks will cost around $6 / kg.
5. Live sand at least $40 for 20/b for Caribsea.
6. A wavemaker should cost around $100 for WP40.
7. You will also need to get some test kits to measure your tank parameters, refractometer cost around $50 for measuring of salinity8. You will need salt mix to mix your own saltwater or you can buy Natural Sea Water (NSW) from LFS. usually cost $1 - 2 for 10 litres.
9. If you are using salt mix, you should get a RO/DI to ensure you have pure water that will not contain silicates. The RO/DI unit will require the replacement of the cartridges once they are exhausted and TDS will go up.
Hope my information is accurate.