I would say that loxf.com, toxz.com, and qhik.com are in the $20.00 to $120.00 USD range based on the fact that they are unpronouncable four letter domains. I agree with what Roogle said about doing some research. You might be surprised with what you find out about certain letter combinations.
As for dropdr.com... it's hard to say. It sounds like it could be a malpractice website or insurance claims against doctors or something! I would try to develop that domain, rather than try and market it.
As for your other domains, I think that tshirtagent.com and keyrap.com are the most valuable out of your listed domains and you might be able to find some buyers based on its name alone, but I suggest going to a big marketing or auctioning area to try and find a buyer, rather than trying to sell it by yourself.