When the new CR is announced, what would be the best strategy if you had it and want to sell it at it's top price. Is it something that you you sell within a few days of the announcement or is it best to hold it over time? Also, when a new CR card is announced, can you get it in a deck for a short period of time or no?
Uncertain. Think of a scenario where some big-time collector dumps most of his collection when CR hits the market. He sets the maximum price now. If you follow that price and sell - after some time some big-time millionaire(s) decides to buy all those cards and he sets the new price (say like...) 35% higher. Then the market starts to saturate but will never go under the previous "right price".
In this scenario you sell for low and have to buy at high to get the card back. You lose money.
The thing is... markets learn. If something happend last time - people will assume it will happen again. That means they try to profit from their observation - thus what happened last time might not... or it might... happen. These markets are user-driven, thus there is no absolutely correct answer.
I disagree with post 7. If a new CR is announced, there will be a massive amount of people cashing and buying packs. Now, yes, some of them will get the new CR, but most won't. Meaning, the guys that dont get the new CR's will sell them on the market, and since lots of people will be doing this, prices will go DOWN. So if a CR is announced, it is much better to buy underpriced cards off the market, save your credits, wait for the CR's to be off the Shop, and when prices go back to normal again, sell the cards you bought underpriced.
On topic, it depends on the CR. If it is useable, like Robb Cr, Noodile Cr etc.. its price will be average, then inflate over time, but will be restricted to a certain amount since lots of people will be using it.
If its a crappy one, like Amiral Cr, Chikko Cr.. it will start off very low, and increase very slowly, since these cards have lots of copies. Your best bet in this one is to trade them for cards that are leaving New Blood, instead of selling it on the market, you'll get more income this way.
If its an OP card, Tanaereva Cr, Caelus Cr, keep it. In a year or two IT WILL increase by huge amounts because of new players, more available clintz, AKA, inflation.