I mean, the easiest thing would be Arena or MTGO. There's also sites like Cockatrice, where people could netdeck or recreate their IRL decks.
With MTGO, there are weird, cheap formats like Penny Dreadful. Pauper is also really popular (decks are a touch more expensive online, but they're still cheaper than Standard/Modern on paper).
I mean, the easiest thing would be Arena or MTGO. There's also sites like Cockatrice, where people could netdeck or recreate their IRL decks.
With MTGO, there are weird, cheap formats like Penny Dreadful. Pauper is also really popular (decks are a touch more expensive online, but they're still cheaper than Standard/Modern on paper).