You architect the backend very differently if you need to scale on day one. Unless you positively absolutely sure you will, I recommend going the single server

You architect the backend very differently if you need to scale on day one. Unless you positively absolutely sure you will, I recommend going the single server route. Amazon AWS is free for a year, it'll give you a rough idea how much money you'll need to spend. If you have the time up-front, spend it wisely and automate server orchestration. Puppet, Chef, etc. (For me Salt works best.) It pays off the first time anything goes down, by the time you should have a plan to expand and hire a sysadmin. Good luck.