The cheapest start would be to get workers. Unskilled ones are around a dollar in wax on atomic currently, I may have a couple of those left i could throw you to help you get in. Those are temp workers and will burn after 14 shifts. Skilled workers currently are about 9 usd in wax on atomic. You won't need a building to use a worker. With a building you will always need a land as well under it. So the cheapest is def workers to get earning right off the bat. You can get them by themselves on atomic or neftyblocks. All packs also come with 1 or 2 asset cards depending on the size pack. Those can be workers, buildings or obsidian. Last pack I opened was killer. It was a creator pack and I scored 3 - Single Digit Mint Legendary cards. plus a worker and matching realm building. and enough creator credits to get 4 buildings. pretty lucky but they land like that sometimes. Those are sometimes cheaper on atomic or nefty too.

The more novo you start with the more you can level up initially. A worker will earn on their own and can rent rest. they upgrade fast if they are not limited by having to upgrade your building also. with both you'll have to always upgrade building first (not res buildings, only resource are like that)