https://www.mtggoldfish.com/articles/vintage-101-vintage-on-a-budget

Islandswamp goes over some budget Vintage decks, including one for under $100!

I don't normally say this, but if you know someone who wants to get into Magic Online Vintage, please pass this along to them. The idea here is to show people that the cost of MTGO Vintage play is much lower than it has been