I too am in this position and have decided to add an addition to my home. You can refinance your mortgage to pay for it and build equity into your home. Why spend the money on rent. Plus all the additional costs, phone, electric, cable, security etc. These are always more expensive when commercial. You can build what you want for a fractrion of the costs. Working at home maked the hours of this business more tolerable.
However, if you plan to have employees one day this can be a zoning issue.
Chris