You really do get what you pay for, so get quality boots. Leather uppers aren't essential, but I prefer them, I think they last longer.
To make them last longer;
Look after them. After you've been playing, brush the mud and grass off your boots and leave them to dry. I leave them near a window for a day-I usually have my window open so the breeze and the sunshine dries them naturally. Never leave them on a radiator, the heat will crack and dry the material.
I clean my boots about once a week. Having knocked the mud off I wash them with a damp cloth (or three, depending on how dirty my boots are). I either leave them to dry naturally or rub them dry with a dry cloth (again, don't use artificial heat), depending on when I need them for.
I then get neutral boot polish and polish all over, including the tongue.