I have 29 Classic Bally Pins in my collection & Most of them NEED the Coin Reject Button, and many of mine could use the Start Button.
I would be very interested in buying in Bulk because I could use so many of them for my personal collection....As for price, if sold by the Set: $4.00-$5.00/Set + Shipping....
Here is a "similar" Coin Door metal part for $1.50 ( Bulk at 10+ is .99/each )
http://www.marcospecialties.com/pinball-parts/A-7478