You not going to find just a code for this rifle. It is associated with the STO retail key; it is not a seperate key.
as i said all i could find on ebay were the Pre Order Codes, people didn't sell the actual game key just the pre order code (only for open beta) and pretended the Rifle was part of that key... i guess they just did not know, it was a little confusing which code did what back then.
I've never seen the actual gamekey with that rifle on ebay.
I am pretty sure if somebody could find some they would sell pretty well on ebay.
Well, I just checked both Targets in my area. Only 1 store had 1 copy, so I bought it for myself (Sorry, Liandras. If I ever find another, I'll let you know.) It was $9.99. So, they are still out there. They are just really rare.
The box has "TARGET EXCLUSIVE! TR-116 Carbine Phaser Rifle" in the upper left corner. It isn't a sticker; it is actually part of the box. Additionally, the guidebook with the Product Registration Key has the same design printed in the upper left corner.
Yes, you can apply multiple retail keys (with different Vendor's Perks) to the same account... I can fly my TOS Constitution class, (equipped with an Automated Defense Turret and Red Matter Capacitor) with the Captain character equipped with the Multi-Spacial Personal Shield, the Rivera Tribble and the TR-116 Sniper Rifle...