I look at it a bit differently. I agree that the economy has a direct effect on the 2nd hand antiques/collectibles market. I am not disputing that at all. That being said, I have seen a dramatic swing in the market from 2009/2010 to now abut I don't really blame the economy as much as I blame multiple factors mostly related to trends, the availability of mobile technology, and TV shows.
For me, I bought and sold stuff for many many years on a very small scale starting as early as 1998. Back them, people would refer to that era as the golden age of ebay. You could sell a scrap of paper on ebay back then. Fast forward to around 2009/2010. This was when I actively decided to buy and sell after being slow and limited in this arena for years. I started going to yard sales, flea markets, auctions, CL calls, etc every weekend (instead of periodically). I filled my garage and a cargo van in the timespan of under 2 years. It was easy and I barely spent any money on this stuff. Selling stuff at flea markets and on ebay was challenging but do-able. Remember, the economy had just taken a crap and many people were unemployed; businesses were shutting down.
Starting just after Christmas (early 2012) I started to notice that things were changing! Garage sales were now packed and every single person there was in the reselling game. If you weren't the first or second person there, you missed out on being able to buy almost anything. Ebay became flooded with stuff as people moved to open online stores with ebay's push to go from an online auction site to an online storefront. Same thing happened on CL.
In the past year, 90% of my deals were made privately through existing contacts and sources. I have almost stopped going to garage sales because my percentages of actually making a score have dropped off a cliff. Same goes for CL. Buying is almost as impossible as selling on there. 9 times out of 10, you end up dealing with someone who is also in the reselling game and no one leaves any meat on the bone for the next guy (Even though it costs you nothing to sell on CL).
I have been using a popular website to buy, sell, trade magic the gathering cards since 2006. Up until last year, I made tons of deals on there (well over 125 individual deals). In the past year, every single person on there acts like they are an independent dealer whose sole goal is to make a profit. people used to trade on that site for the fun of it (non profit related motives).
That all being said. My point is that greed has basically taken over at this current moment. I understand that many people have turned to reselling as a means to pay their bills or to earn a living. That is a major factor in what has increased the number of people doing this nowadays. However, I believe that it is a current TREND, as in it is popular, to buy and sell on the secondary market. Ebay has made it easy to look up prices especially if you have a smart phone on your hip at all times. TV shows have brought such activities into the mainstream limelight. Those who did not previously know what an antique was now realize (after watching a cool TV show) that IT IS EASY to buy and sell them if you have an ebay account and a smart phone.
Making a quick buck is all we care about anymore. This is ultimately what is souring the market. Simple as supply and demand. You need buyers in order to sell. I am saying that it is not solely the bad economy that is creating a lack of buyers. There are too many sellers and the market is flooded. It takes almost no skill to do this NOW. Why buy, when you can sell? Not to mention the people who used to be the BIG collectors, hence buyers, are getting older and are no longer collecting for a multitude of reasons.
What can we do? Adapt and persevere. Discover what the new younger market is buying and switch over to buying and selling that stuff. Also, wait it out. Eventually, people will get frustrated and give up and as most trends do, this too will pass, eventually.
Good luck out there, friends!