If budget is your main issue and you want to try out, rather than dive into, fpv then a iPhone in a BlitzWolf enclosure is only about 30$ if you have the phone. You can use DroneVR app to display your fpv view on the phone, and it's free for the first couple of short test flights and only 10$ to permanently unlock the Phantom4 feature.
It's not the best option but it is the cheapest option that's worth bothering with, and it will let you tryout fpv without investing the 500$ plus of a 'real' fpv system.