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