Hi. I believe you seem to misunderstand the developers' intention.
There is no obligation for anyone to do any sales of any sort, regardless of the time of year. Since it is known that Robux are not sold in any increment less than 400, the developers are under no obligations to adjust themselves to fit your spending choices. I do feel sorry for you, as Vesteria is an amazing game, but the way you spent your Robux indicates that you rate other games or gamepasses higher. I wish you luck in your search for more funding.
Kindly, Devilsknife1.