Here is a thought on the matter. Maybe if people was able to sell these items for there true value. And not be forced to sell way under the price in time and or raw materials to make said items. People will be more inclined to sell them rather then just sit on them. But hey what do I know, right.

Nah, that would be evil.

Now, should the same thing happen with items those players have listed for sale, potentially removing stock from the market when something suddenly becomes valuable (like happened with BMCs, for example)?

This doesn't happen like you think it does. I often flip market goods in MMOs to make a lot of money but you have to remember that it 1. Takes a crap load of time to do the market research, figure out the trends and realize what can sell for that moment in time. 2. People value different things at different rates for different times. Meaning, if you buy something for $100 and you can sell it for $300 tomorrow, but after tomorrow you can only sell it for $35 and you couldn't sell enough before that happens, you're screwing yourself over.

So you can't just buy everything on a MB and sell it back. The natural laws of supply and demand still exist even if you buy out markets. You can manipulate it to some degree but you can't control it. PA also gives away goodies all the time which adds to inflation, so you can't store things for too long or else the freemium daily login rewards will screw with your profit margins.

But in other mmo's, yes, you can absolutely do market flipping but it is a huge time sink and the amount you get back is generally about the same if not slightly better than other means if the game is designed right.

I don't know what the perfect "experation date" on postings should be?  I posted my requests for 40 dyes in the market back in August, now I am down to 9 in and 31 still out.  But according to some users here, I wouldn't be able to get any dye at all, if all my requests expired back in September. 

I think the whole thing is a logistics nightmare,  on one hand you have a set price for product, and on the other hand you have a bidding war. Instead of a queue line with backlogs, the CM would be an eBay sniper paradise.  Players would see a low bid about to expire and snipe it on the last minute. 

Back in my days of playing the original Guild Wars, there never was a central market or auction house of any kind.  To this day, the players on that game head over to Kamadan and openly trade goods.  Problem is the RMT are in there spamming ads as well.  That is why we can't have nice things in these games.

Have fun!

after how long 1 month or 3 months or 6 months?

I like the idea, but what's the actual data?  

Look at preorders on Flame of Despair as our example.  

If we did implement a weekly renewal requirement for orders, what impact would it actually have? How many of those preorders actually are from players who are so inactive they couldn't renew their preorder on a weekly basis? Is this actually a problem? It sounds good in theory, but what is really happening and does this actually substantially address a problem?    

One thing I would like, may be another topic - is loosening the restrictions on minimum/maximum prices of items.  Maybe Flame of Despair really should be triple its price if the demand actually exists for people to still want to buy at that price. Would that really cause problems?  

It would not adress the core issue, the garbage market, however PA don't believe in capitalism, hence they never fix that.

Also there are a lot of inactive orders on the market, and while it would not make drastic change, deepending on item, the number of orders would drop 75-50%, which would help a little.

max 1 week preorder is more than enough

It never occurred to me that people not even playing the game were part of those 3000 pre-orders on Flame of Despair. I have been waiting 3 months for one myself and check several times a day for it. Maybe the Central Market should have PO reset to zero one patch day a month. I wouldn't mind re-POing every few weeks. If you win the lotto and don't check for/pick it up in the CM within a month, you deserve to lose your PO. I think having a PO reset every patch day might be too stressful when you have a hectic real life.