The falling cost of building a wireless network from scratch could entice a new player into the US market, say analysts at BTIG Research, especially if they could persuade Dish Network to part with its desirable midrange spectrum. There has been speculation ever since Dish acquired its first spectrum, from two bankrupt mobile satellite operators, that the pay-TV firm did not really want to build its own cellular network, as it claimed, but would wait for the right time to sell its assets at a profit. Dish has continued to amass spectrum, and is bidding in the currently ongoing 600 MHz incentive auction, but there is still no sign of a network build-out, either to enable a quad play for…