In posing this question, I realize that it may be out of scope for boardgames.SE; this question could be subjective and the monetary costs vary quite a bit between cheapest and most expensive decks. Having said that, I think this could have value if it falls within the Q&A format appropriately.
I've been a casual player for awhile, but I've rarely dabbled in tournament formats. I think I spent some time between Mirrodin and Ravnica playing Standard, but beyond that I have had very little exposure. I am realizing that I'd like to start participating in the more competitive tournament side of Magic, but I'm concerned about the cost.
I get the sense that it is a much larger initial investment to start in Vintage and Legacy because there is a solid base that most decks use in land and mana artifacts, and the upkeep may be minimal as new cards come out that fit a deck, whereas the initial cost in Modern and Standard is lower, but there are continual costs as new sets come out that consistently change the format. Beyond that, I don't have a great sense of how much these costs are, and the average costs of these would partially determine what style of tournaments I'm likely to be attracted to.
What is the average cost of a deck for each of the major tournament types? These would at least include Vintage, Legacy, Extended, Modern and Standard, plus any others I may be unaware of.