I beat this battle over 7 years ago now, I only buy the cheapest last year model that is available, they all meet my needs and I know they will be worthless in no time. If you want to dump your money keep buying expensive cameras.
The only exception to this rule is where you make more money from your camera than it costs, then you have a good business case.
Brian
In the last five years I have bought, used and later sold for profit, the following cameras and lenses.
Canon 5d Mark II. Bought used from an unclaimed baggage store (had 25 shutter actuations) I used it for almost 75,000 shots. Sold it for $300 profit
Canon 7d. Bought used on Craigslist with 3,500 clicks. Sold on ebay a year later with 25,000 clicks for $100 profit
Canon 5d Mark II. Bought from a studio that was trying to stay afloat. It was a 20,000 click body. Kept it as a backup for a year and a half. Sold it for $50 profit.
Canon 70-200 2.8. Bought used on Craigslist. Used for three years. Sold it for $200 profit.
Canon 85mm 1.2L. Bought used on Ebay. Sold on Craigslist for about $20 profit after using for two years.
Canon 24-105 bought used from Craigslist. Sold for $50 profit two years later.
Currently I use 5d Mark III bodies. Bought on deep discounted Ebay sale. Got both new about a year ago for $2500. Love them so much, I won't be selling these for profit.
Canon 300mm 2.8 IS. Bought used for less than they are selling for on ebay today, three years ago. Not selling it.
Canon 85mm 1.8. Replaced the 1.2 for faster AF (sports). Bought used for less than used ones fetch on ebay.
Canon 135mm f2. Traded a lens ($200 more credit than I paid) plus cash (for a total of $300 less than they fetch on ebay) on Craigslist.
Of the tons of Canon gear that I have bought and sold, I have never lost money. The lenses I bought new aren't going anywhere (I bought them new because I new I would always use them). The stuff I buy used and sell is so I can use the gear without having to throw money away renting it.