Running a co-working office is not just leasing an apartment, giving 5 people a key to it and ping them once a month to deposit 200$ in your account or the cookie jar on the kitchen table. I've watched this happen from fairly close twice now, and here is a selection of what is involved:

- Internet/telephony. One residential internet point with a wireless router isn't that big a deal, granted, especially when the people working there are tech-savvy. But you very quickly get to the point where somebody needs a fax (government contracts yay!), a reliable line to Skype while that other guy is pulling in a new Redhat iso ('DD-WRT can do that!' sure, if your time is free), needs a way to have phone calls go to an answering machine, or if you need to decide on a system who will answer whose phone when people have varying work schedules. Everybody cell phone only, no-guarantee internet - it probably works in some circumstances, sure, but you hit the limit sooner than you think.

- Rent is not the only cost - you need to divide electricity, water, municipal taxes, garbage costs. Can easily add a double-digit percentage to the base rent.

- Who's going to do the cleaning? Put out the garbage? Call the land lord when the toilet is clogged? Answer the door for that client that you thought was coming at 9h30 but came at 9h (happened to me this morning)? You can pay somebody for all of this, but it'll add to the cost. Some people will want to do it themselves, others will want to pay somebody - now what? Resentment creeps in easily.

- One person decides to get a regular job, or to go on holidays for 3 months, or doesn't make enough to pay rent. Now you have to scramble to fill that spot, or jack up the price of the rest. If you're connected enough that sending out one email will provide you with enough reliable candidates, great - otherwise enjoy spending an afternoon posting ads online, showing people around, interviewing them to at least have the impression that they won't rob you or leave you high and dry with the bill after 3 months.

- Or somebody wants to hire a secretary or other staff. Now what? Labor law rules, higher and more insurance, parking issues, and no more 'I can just leave my wallet and 2000$ laptop here cause I know and trust everybody', that's what.

All in all, what you can save over a commercial co-working arrangement (which, yes, are expensive) is in using hobby-level equipment (no Cisco switches and IP phones, only the cheapest from Newegg, and Ikea over Aeron); and the profit they make. That profit isn't all that huge, although in a small team you do have the advantage of being at full capacity as long as you have tight arrangements. Co-working spaces go bust all the time, not because they're so expensive, but because doing enough business for economies of scale to kick in is hard in a space that doesn't require much except capital to get into. So in my experience, you can bring the cost down from 500-700/month to 300-400/month plus depreciation of the chair and desk.