Hi Russell
The bottom line is that you will still need some kind of signal coming to your house whether that is by cable, phone line, or by picking up somebody else's signal be that somewhere like Starbucks or your neighbour. In order to use somebody else's signal you would not even need a router but simply a wireless usb dongle or network card in your computer. Usb is the best option as you would not need to open up your computer to add new hardware. You must be aware that if you pick up somebody else's signal your connection may be slow and you will be subject to the owner's whim should they decide to turn it off at night or when they go out. The other downside is that many home networks are now secured using either WEP or WPA passkeys and you won't get access unless the owner tells you that key.
This can work though - my brother and his 2 neighbours in the flats near to him share the cost of 1 broadband connection and have created themselves a little wireless network.
Hope this helps
All the best
Ian