I purchased a Tp-Link Archer C7 router at a thrift store for 5 dollars. Brought it home and flashed a specific revision of open-wrt to its firmware, and then ran an update file on top of that firmware revision to turn it into a pineapple router.

Had no idea if it would work when I was doing this.

Works great, the 5 bucks was totally worth it, and now I can use it to test hardening on my mobile devices.