If you're new to Snapfish and order 50 or more photo prints you can use this voucher code to get 100 more prints absolutely free.
Discount: 100 free prints when you order 50 or more
Expiry: 30th September 2013
You'll have to register to join the site but it doesn't take long. Then simply upload your prints, place an order for 150 6x4" prints, and pop the promotional code in the box when prompted at the checkout stage.
This offer excludes free prints, print credits and prepaids, and only applies to new customers purchasing 6x4" prints.