Definitely do lots of research first! Your WAY better off getting a drilled system with a sump and skimmer. It costs more but is definitely worth it. Saltwater takes a lot more time as well so just be ready for that one. There is more routine maintenance, water changes, skimmer cleaning, water tesing, etc. Also, the cost of the salt itself and the fact that you would want to purchase and RO/DI water filter, powerheads, auto top off, rock at $3 / lbs. etc. etc. It's a GREAT and rewarding hobby! I just want you to be aware of the cost difference because everything does add up. Finding a nice used setup is all ways a good start as well. It saves you piles of money as long as you know what you are looking for.
Saying all this, you can just change your tank without going to a drilled tank. You would just need a HOB skimmer instead. But all the other costs would still be there.