GPS on Ipod touch?

[theipodkid]

Hi there,

I go out on my push bike a lot and use it too get every where, but. I want to get GPS.

I could just use something like a Garmin Edge 800 but I don't fancy paying £200ish. So, is they any way I can get GPS on my Ipod touch 4th gen by buying something I pug into the ipod itself or is they no way?

Thanks