There has to be a harmony between the dough, oven and method of baking (e.g., using a pizza stone, screen or pan, bake time/temperature, etc.) in order to get the best results. Pizza screens were developed to be used in commercial conveyor ovens, which are typically high-volume operations. They are favored by pizza operators who use conveyor ovens because is is easier to train workers to assemble pizzas on screens than trying to teach them to use peels and loading the pizzas into a deck oven and then moving the pizzas around in the oven to get the proper bake. With conveyor ovens, unbaked pizzas are put in one end of the oven and they come out the other end. In the U.S., most of the major pizza chains, like Pizza Hut, Domino's, and Papa John's, use screens and conveyor ovens. Also, their doughs contain a lot of sugar, which makes screens a good choice. If their pizzas were baked on a hot stone surface of a deck oven, the bottom crusts would most likely turn prematurely brown or even burn.
Many of our members, me included, use pizza screens in home ovens. I have used them alone for certain styles of pizzas, such as the American style doughs with a lot of sugar, and I have used them together with my pizza stone, especially when I want to make pizzas that are larger than my pizza stone can handle (the maximum pizza size my stone can make is 14"). As between using a pizza stone and a pizza screen to make the same size pizza, I would use the pizza stone because it will produce a crispier crust. That doesn't bother some people so they will happily use a pizza screen. Using a pizza screen also avoids having to heat up an oven and pizza stone for an hour or more, which can be an advantage in the summer when high temperatures can make it uncomfortable to heat up the kitchen just to make a pizza.
You can see an example of the use of a pizza screen/pizza stone combination at Reply 25 at http://www.pizzamaking.com/forum/index.php/topic,7689.msg66268.html#msg66268
. I recently used the same method to make the pizza (18") shown at Reply 301 at http://www.pizzamaking.com/forum/index.php/topic,9068.msg98561.html#msg98561
. You can read more about this method, and some other variations as well, at Reply 45 at http://www.pizzamaking.com/forum/index.php/topic,2223.msg20965.html#msg20965
The pizza screen you referenced at eBay looks fine. Before using aluminum pizza screens for the first time, most people season them. If you decide to get a pizza screen, we can advise you at that time on how to season it (there are several posts on the subject). You also don't want to let very high hydration dough skins/dressed pizzas sit on pizza screens for other than a brief period. Otherwise, the dough can seep into the openings of the screen and result in a pizza that can't be removed from the screen without damaging it, in some cases, fatally.