I also usually keep one baby from a litter, as long as it is as good or better than the parents. But I do sell companion rabbits.
I am very careful about who I sell to, I spend a lot of time making sure they know what they are getting into. I also don't let my Flemish go until they are about 10 weeks old. The young rabbits come with food and a health care booklet, and a lifetime of help and advice. I also make it very clear that if they no longer can keep the rabbit, I will ALWAYS take it back, no questions asked. (And I have gone to great lengths to get back a rabbit if necessary.)
I've been very lucky so far. And a lot of my bunny owners keep in touch with me, years after they get a rabbit. I get Christmas cards, emails and photo's all the time!