FYI, K-5 CTY math is licensed directly from EPGY. The entire interface is EPGY. Only difference is that you get a CTY rather than an EPGY tutor, and CTY has its own written (as opposed to online)final exams. Because it's licensed, it's cheaper to get it directly from EPGY.
As for science at CTY, that's CyberEd. They mark it up 8000% from what you could get from Homeschool Buyer's Co-Op (I bought it for $32 for a year vs. $640 for 3 months) but it's no longer available. However, HSBC is negotiating to buy it and sell it themselves, so watch their website for bargains.
www.homeschoolbuyersco-op.com You don't get a tutor and the software doesn't keep track of your child's progress, but doesn't seem to make a difference to us. Also, even though CTY says 5th grade math is a prerequisite, we've seen no math in life science or earth and space science.