Are there any sub $100 gps devices that can export a gpx file I am looking to ride with strava, however as a teenager I receive very little to no money regularly and I do not have a smart phone. I would like a device that tracks my ride via gps and exports a gpx file so I may upload it to strava. It must cost less than $100 AUD.
Instead of an actual GPS device, I would recommend buying a used smart phone, (The Strava app itself only works on either iPhones or Androids). A "Nothing Special" used smart phone you can usually find for maybe 40 bucks, depending on the model and brand.

Download the app and just take the phone with you wherever you ride. It's not a fancy system, but it works. This is the method I use now.