We love Math U See and have multiple friends who live Teaching Textbooks. A major plus is that both of these go thru calculus!
We love Teaching Textbooks for math, and if you look online, you can usually find them used for cheaper. Khan Academy online also has a ton of resources for various subjects and is free.
I found some amazing things and resources on Pinterest.
rightstartmath, Steven Spangler science, Khan academy has every thing, night zookeeper?, Spark math, xtramath, mathseeds, splash learn
IXL isn't cheap (about $150 price tag for the year) but it is more interactive and can be more self-guided for both math and science. It also has ELA social studies and Spanish stuff and for math and language arts a way to assess and find skills your kiddo is stuck on. Science is a tricky one to have self-guided as it's all very hands-on. I'm not sure how helpful this is but that's currently where I'm at with it.