I've recently started playing MTG. It's me and a friend of mine. We play casually, we don't care if cards are old or rare, we are just looking to purchase some cards to build a few decks (ideally 4-6) that make at least a bit of sense, meaning containing some 4 to 5 rare in each. Something like starter deck kit, that we already bought (2017 and 2020). I was thinking to buy in Cardmarket, either lots of common/uncommon/rares and out together whatever we get or by singles, but I don't know which list to use. The lists I found are too expensive for me. Ideally each deck should costs around 5-6 bucks. What do you suggest? What do you think about buying a couple of jumpstart booster packs each?
Approach 1: Buy cards for cheap, for example from eBay or whatever the most popular used items market is nowadays. You will always find someone giving up their hobby and selling their collection in bulk. Ask in your local game store if they offer cards in bulk. In either case, while the used card collections usually contain rares, don't expect high-value cards to show up, so optimise for price per card.
Approach 2: To start with, play Pauper or Artisan in which the maximum legal rarity of cards is common or uncommon, respectively. This allows you to focus on your existing card pool; you don't have to focus building around probably sub-optimal rares and saves you from having to hunt for stronger and thus more expensive rares until you know that Magic is the game for you.