A prototype of a Lightning to jack adapter

Seen on eBay for $60 (which is 6x the price of a standard adapter), a Lightning to jack adapter.

A prototype iPad nano 7G

Seen on eBay for $240, a prototype iPod nano 7G.

A prototype iPad 2

Seen on eBay, a prototype iPad 2. It is listed for $480.

A prototype iPad Pro motherboard

Seen on eBay, a prototype motherboard for the first iPad Pro.

A prototype iPhone XS

Seen on eBay for €3,200, a prototype iPhone XS. One reason for the high price is that certain security protections can be bypassed on this model.

Some LaserDiscs directly from Apple

Seen at RR Auction, an interesting lot: Apple LaserDiscs with a player that was used at Apple.

A prototype of the VideoPad 2

Seen at RR Auction, a prototype of the VideoPad 2, sold for around $26,500.

A transparent mouse prototype

Seen at RR Auction, a prototype Macintosh mouse. It is transparent and (most importantly) sold for over $14,600.

A prototype of an eMate 300

Seen at RR Auction and sold for a bit over $8,500, a prototype of an eMate 300.

A Pippin prototype

Seen on Mercari, a Pippin prototype.