I have one going into high school and one going into 7th grade.
I agree with @Christy on PA Homeschoolers and Wilson Hill.
I also agree that there are tons of decent high school texts out there for peanuts, if you know where to look. The Well-Trained Mind boards have lots of recommendations on the threads. You can find old Dolciani, Foerster, Jacobs math texts, Spielvogel for history, and lots of Prentice Hall/Glencoe texts on used book websites. You may have to hunt for a TM, but often there is little change between editions, so you can often use a TM for a different edition with little modification.
Also, many of the Catholic satellites use good texts for high school and come with syllabi and test support (Kolbe, etc.)
I like Miller Levine and Cambell for Bio, Chang for Chemistry, and Hewitt or Knight (depending on whether you want an early Physics or more traditional, respectively).