Your confirmation email should include the purchase price you paid, as well as most of the information that you need.
But, if you need something to verify the transaction took place, we can arrange something. If you made a purchase with a credit card on the Paint Nite, then contact Customer Service at Info@PaintNite.com, and request that they send you a receipt.
If you made a purchase through a deal-a-day site (Groupon, LivingSocial, Amazon Local, etc.), you may need to contact their customer service to request one.