The Guitar Man PU2E Undersaddle Acoustic Guitar Pickup is a great way to amplify your acoustic guitar. A great value way to make your guitar electro-acoustic.
This item from Guitarman provides you with an under-saddle pick-up strip and an endpin jack.
The pickup has the attached wire which needs to be soldered to the endpin.
The endpin fits in the same place as your existing strap button - some drilling may be required to fit the new endpin.