if you are at a planning stage, then research options like altcoins mineable with GPUs too. Bitcoin is currently not mineable with GPUs.

What you need to consider is not only the equipment cost (be it GPU rigs or ASICS) but the difficulty (both current and future estimates), electricity costs and obviously future prices.

There are calculators available that do the calculations for you and can tell you when in future you will have the break even point. Google them.