We use k5 learning. It has an option to sign up for 199 a year or 25 a month but I just use it for the free worksheets. My son hates works sheets (too mant problems on a page overwhelm him) so I copy them down a few at a time on the white board.
Math Mammoth is a good one, if you like mastery type math curriculum. It's working pretty well for my daughter, strangely, who probably has LDs, but not my son. Saxon is pretty good, too, if you like the spiral method. We're using Saxon 5/4 for my 9 year old. He says it's harder than MM and isn't as boring, since it goes over things from previous lessons and not just the new stuff. I don't think my kids are advanced. hth.
I believe Saxon Math is perfect for typical kids. It's a spiral program and past lessons are continuously practiced - which, imo, is the best way to retain what you learn in math. Saxon explains everything wonderfully, then has about 5-10 practice problems on the new lesson, and 30 problems of review. My ds has become so good at math using this program. We started with Saxon 76 in 6th grade and now he's doing Saxon Algebra 1/2 for 7th grade (some people use Saxon 87 instead). We take our time and usually spread a lesson out over 2 days. Even though I've tried to change to something else (just for variety), ds always asks to go back to Saxon. So, we plan on using it for the long haul.
There are plenty of naysayers out there and I believed them so I stayed away for years. Thankfully, I finally gave it a shot. It's plain, simple, and to the point. Ds does the problems on a white board. Math takes us 30 minutes a day.