Where you live, the site itself, soil quality and the type of wine you intend to produce, the yield you expect, predators and the long timescale involved to mature the vines, plus the cost of vines, poles, wires, netting, fungicides, equipment such as fruit crusher, press, fermenting and storage, bottling, corking and labelling need to be considered. There is also a great risk that the wine produced may be rather disappointing, as well as being very expensive. I speak from experience. Currently, the cost per bottle from my small (2 allotment) vineyard is about £25, even though I pay no rent, and the quality is not that great. Theoretically, the cost should decrease significantly in time, but damage caused by the winter storms have imposed extra cost. Although no actual flooding has occurred, the waterlogged ground, the high winds and heavy rain have prevented me from completing the complex and essential task of winter pruning, which requires expertise.
Nonetheless, I still consider the pursuit of homegrown wine worthwhile.