I've seen those on ebay too. I did a search for Plus Lighting LTD and found their web site, but they don't give any specs on their bulbs. Also, I saw the feedback on a few of those sales and some said they were too yellow to be 10K. I think I saw awhile back a few people were selling the same bulb...used. So with all that, I really can't say of they are good or bad.
I've always used Coralife bulbs and have been happy with them.