Talked to a CPA about this last week (USA), and I'm going to operate as a sole proprietor. There are very few fees in my state for this; the only major one is personal property tax, which is about 3% of the depreciated value of any personally owned business hardware if the total amount owned is over $10K. Under $10K and you're exempt. The rate of depreciation is 20% a year I think, with a 25% final value minimum. For investors (I only have one potential), I'm basically just working it like a hosting service. If I host your hardware, you chip in for my expenses/power/etc. and I take a small fee of what's left, then you get the rest. There's no protection for investors this way though, so it's more risky than if I were incorporated. It's the same as a personal loan with no promise to pay back. Most people won't invest in something like that, and I'm fine with that (less work for me).
Running the business out of my house allows me to deduct a major portion of my home expenses (insurance, property tax, HOA fee, power, possibly internet, etc.). The only downside is if I sell the house without shutting down the business for 2 years, and I get a capital gain, I have to pay capital gain taxes on the portion of the house used for business (there's no $500K exemption on that part). Something to keep in mind if you plan on selling your house..
Be sure to read up on the concept of unlimited personal liability as it relates to a sole proprietorship. You indicate you own your home. Your home is now an asset of your business, and so is everything in it. Your car, you bank accounts, any personal assets, TV, stereo, other property, real estate, stock bonds, mutual funds, anything in your safety deposit boxes, etc. So say you host 10 rigs and someone breaks in and steals them. Now lets say your insurance doesn't cover it and you can't pay out of pocket in full (asset rich but cash poor). The owners can sue you personally in court and seize your assets (everything you own and even your future earnings) in order to secure their claim.
Also be sure you understand the tax implications. Say you make $50,000 profit the first year but being a smart business owner you decide not to spend it and keep it in the business to grow/expand the business. As a sole proprietor the instant you earn the profit you incur tax liability. The govt eats into your profits and there is no sheltering of taxes. This makes it harder to grow and expand the company. Even keeping profits as cash in a bank account to expand your working capital has the overhead of upfront taxes. Granted you could cheat on your taxes but then all your personal assets become subject to seizure by the IRS.
