I always say, if you want big get it because you'll end up upgrading anyways. If you do start small, invest in components that will also work or are modular with the tank you want in the future. I've done this, while its pricier upfront, it's much cheaper in the long run.
LEDS are great, they seem expensive but with reduced power consumption and no bulb changes, in 2-3 years the pay for themselves. Many LEDS are modular so if you upgrade, you just add units. The same goes with DC
return pumps. They operate way cheaper and if you get a bigger one, you can reduce its power setting to reduce flow. An AC
pump runs @ 100% all the time and flow is controlled by a valve.
You can DIY additives and keep cost down, buy salt on Black Friday/Boxing Day for the year etc etc.