The far easier option that you mentioned is the wifi usb dongle, and it is only 8 bucks so it's an easy and cheap fix! You just use a usb port on your computer, and it allows you to connect to wifi. The dongle  can be found here:USB Dongle

If you have an older computer without any spare USBs, you can get a wifi extender that has a ethernet port on it and running it to your computer, and can be found here: Wifi to ethernet