Where do I get this 6.5 mHz crystal?

The crystals can be ordered through many different electronics parts distributors for around $1.25 a piece.
Some popular ones are:
Mouser Electronics
Digikey (call 1-800-DIGIKEY)

a slightly more expensive alternative would be to purchase from your local Radio Shack through special order.

xtort(a.k.a. optic) graces us with this little bit of knowledge..

   [here is] the part number of radio shack's
   6.500 mhz timing crystal to avoid to hassels when radio shack
   employees will ask you what the crystal is for ;)
   sku no.  10068625
   discription  Timer Crystal
   price: 4.99

   it's a special order and u add 1.00 for shipping