It may be true that we'll never hear from the OP again but I don't concur with what Bigbearjedi posted so I will post my experience in case someone else reads this thread while searching for info on the same subject.
First off, I don't believe the OP was talking about using his phone as a Hotspot, he was talking about using one of the various windows apps out there that allow you to use your laptop or other wifi enabled computer to create a wifi hotspot in order to share that computer's internet connection with other computers. If that's all the OP wants from a router then the answer to his question is that he doesn't need to buy a router. Just keep in mind that your laptop now becomes a router, it needs to be on and running for any client devices to be able to access the internet.
As far as using an app on an Android phone (I have no experience with iPhones), I use an app called PDANet on my Android phone (have used this app on multiple phones over a 5 year period or so) and it works great to share an internet connection with other devices. I don't know off hand the max number of clients that can connect but I have had 6 or more devices connected to my phone's wifi hotspot with no problem whatsoever. I regularly use my phone's hotspot in my RV when I travel and typically have 2 Smart TVs and 2 laptops connected.