I'm confused as to where you got them from - I assume you didn't get either from a reputable breeder or a rescue? Because with such young kittens that you've had such a short time I'd always say return them to the person you got them from. Most rescues will take back a kitten if it's obvious it's not going to work out within a matter of weeks. And as I said earlier, a reputable breeder will not only be willing to take back a kitten in these circumstances but would request it. But a reputable breeder would not sell a kitten under 13 weeks.
As to selling them - I can understand that you'd want to try and get some of your money back but it does sound as though you've paid over the odds for them, for the BSH at least. The price you quoted is, as far as I know, towards the top end of what I'd expect to pay for a pet quality kitten from a reputable breeder, fully vaccinated, 6 weeks insurance etc. I don't think you can expect to get anything like what you paid for him, although it is always good to ask for a small fee/donation for any cat.