What do you consider nice? What are you including in the $500 price?
Included in the price is probably around a 20 gallon tank, diy stand, heater, light, hob filter, powerhead, sand, salt, mix of ocean liverock and dry rock. That should put you close to $500.
Then you can add corals and fish as you choose. Here locally you can buy coral cheap through local hobbyists.
Won't be any sps Instagram tank but can definitely make a successful and beautiful softy/LPS tank.