You can buy an external hub that plugs into a usb port, and provides more - from 2 upwards. Don't forget that a 2 port hub is only providing one extra port.
Some are powered by your pc, others are plugged in. If you are using a desktop and have a free plug socket handy, I would go for that option. It is more able to support high powered peripherals.
You can pay anything from �5 upwards. Some have a novelty aspect, shaped in different ways, others are plain box affairs. Here is a selection - I am not recomending any of the products or the seller, just showing examples of what is on the market.
http://tinyurl.com/339xxp
If you search for 'external usb hub' you will find lots more.
Another alternative is to fit an internal hub to your pc. It's not difficult.
http://tinyurl.com/3a9jt2