I purchased two brand new iPhone SE's for $100 each around black Friday from Straight Talk. Required one month of prepaid service and then they were unlocked, I used them down in South America.

The iPhone SE is better than any comparable Android phone and will receive updates for another 5 years.

So "You can't find a cheap new iPhone" is not true. If you're willing to take 1 extra step and get a month of prepaid service you can get a cheap iPhone.