Amazon has it’s own Sonic Boom:Rise of Lyric pre-order offer separate from GameStop’s deal. This one is costume-based DLC that gives Sonic and Crew sports tape a huge glow. Here’s the details from Amazon’s site.
Pre-order Bonus Offer – Get Exclusive Luminous Costumes
Pre-order at Amazon and receive a code to unlock exclusive luminous costumes for Sonic, Tails, Amy and Knuckles. Code will be delivered upon shipment. Offer valid when shipped and sold by Amazon.com. Amazon reserves the right to change or terminate this promotion at any time. Offer will be extended to all existing pre-orders.