If you price out the top 5-6 decks from the world tour, the average price is well over a grand
there's not many 'budget' decks anymore that are competitive at a tournament level. Used to be able to get away with a deck full of common/uncommon zombies/goblins and do relatively well. We had a person play 8 total rares in a goblin deck and go 5-3 at a regional tournament. I think his deck had maybe $100 worth of cards in it.
Definitely can't do that anymore, the metagame doesn't allow for it.
Drafting is relatively inexpensive, but I was never a real big fan of it. Too unpredictable for my liking.
Constructed is quite expensive - I won't argue with that. :)
Pauper (commons only) is a cheap constructed format, but it isn't well supported by Wizards of the Coast. There's also Standard - the average price of the deck that won 2016 World Championship in the format is $257.93, as you can see here:
http://magic.tcgplayer.com/db/deck.asp?deck_id=1269660
The average price of the most expensive deck from the top 8 is $399.96:
http://magic.tcgplayer.com/db/deck.asp?deck_id=1269658