As you can see in the portrait thread, it’s just a bunch of glasses, hats, wigs and fake beards. That’s surely not expensive.
Yes, and?
Bonus does not decline to “boni” in any sense meaning “perk” so my point, and correct Latin, stands: the plural of bonus in Latin, is bonus and it’s bonuses in English.
Stop mangling it. It’s been dead for many a century now. 
Well I know now it was too good to be true already - With their great month old news I am forced to read every day if I want login reward - I guess it was naive to think someone in gaming industry would be actually nice. Whatever, next time I will not try so hard to be positive. My apologies.
Well, if it was used as an asjective, given the original sentence, it would be accusative so it would be boni. The thing is you are right that using it as a noon, the only way to read it would now be plural (with no declention).
(whilst it is usual to use boni in French for exemple when it is plural, in English, it does seem less usual, but it still odes exist according to https://en.wiktionary.org/wiki/bonus) 
That said, beyond the googling exercise, i have no real stakes in the final outcome of the “bonus” question 