Damocles wrote: lets say this new product is known to be marketable, then the economy can behave in certain ways:
-it replaces demand for another product or competes with it. Anyhow, the price or traded amount of the competing product will drop,
as more funds are redirected to aquiering the new asset.
-it can be priced, if the utility (complex) and supply-costs (easy) can be determined.
-new production facilities are build / or reconfigured. eg: it changes the "landscape" of the industry
-or not much happens, and its just a unique item, that receives a high market-price in an auction.
-it "outlawed" by some regions. but that rather outside the pure economic view of the model.
I would think that some things might replace others, but in some cases it might just be more of an added value kind of thing so wouldn't necessarily replace the demand for a certain product but rather it would probably break down the market share for that particular kind of item into more discrete elements. Richer people would tend to favor the higher value one while the general masses may stay with the original, so I guess in that sense it would be competing with it, sort of.
The other thing is, it almost seems like you could be suggesting this although I'm not sure, a "new" item would be pretty expensive at first, but as time goes on the price would drop as the cost of production/resources/fabrication becomes cheaper as well as more people creating knock-offs etc create competition, until it hits the threshold of cost to make and asking price. Heck, you might even be able to get a good deal once in a while for various reasons where the producer is selling at a loss, like maybe going for volume of sales or a going out of biz sale. Thing is, at least for a game, things could get pretty complicated fairly fast.
Sure would be cool to try and pull it off, or at least a reasonable facsimile thereof. More power to whoever manages to do it.