Well may I know the reason of selling. If I am not wrong then I think I have seen you guys had your signature campaign only a week ago?
There is no personal promotion specialist and no budget to hire a professional. Making the game was fun, but it's half the success. Career promotion is required - we do not know how to do it. for sure someone else can do it.
if you want to sell it it's your choice. but if you are just doing it because you don't have budget to hire a professional then you can find a partner. there are many skilled people who can work for you for a partnership bases. you can share the project revenue with him. I think it would be an attractive offer for a promotion specialist.