I don't know why this demoralization but not everyone is ready for "big" tank. Many long term hobbyist proceeded to big tank gradually as they gained knowledge and maturity in this hobby. Alongside, looking at someone's tank and thinking "man thats sooooo cool I should have it", cashing thousands of $$$$ only to find that the hobby doesn't suit his/her need would be awesome right? Yes, go big!!!!! But be 1000000000000000% sure you can keep it "properly". A big tank will not be "automatically" stable by itself, you will have to make it. With effort. You just get more room for error with bigger tank than with smaller tank but with proper knowledge, makes little to absolutely no difference.
And about the $400 budget. I replied to your last thread about it that I started my old 20 gallon tank with just $200. I don't know why its a "LOL" or "best of luck" matter. Just a heads up, I even didn't start it with 2nd hand stuffs. Let me do a quick breakdown for you:
1. 20 gallon tank = $50
2. LR (20lb) = $100
3. Powerhead = $20
4. Sand = $20
5. Light = $100
6. Filter = $80
7. Test kit = $30
8. Heater = $20
There you go, $420 (sorry for the extra $20) for all the equipment you need to start a reef! Not everyone needs fancy mp powerheads, LEDs, controller and other fancy stuffs to get a proper tank running.
To OP: Get the led off the chart unless you get some freaking good deal which do happen from time to time. You just have to be here at the right time
