It's not absolutely idea for you, but it might be worth considering ALEKS (
http://www.aleks.com ). It's much cheaper than the other alternatives, and there's a free trial, so you might want to consider this first and move on to more expensive options only if you need to! The negative, for your needs, is that it doesn't have great teaching. There is an "Explain" button under each question, but this gives a step-by-step "how to do this question" page without all that much in the way of explaining underlying concepts. However, you might get your DS to try this first, and ask you if he needs further help, especially if a lot of what he'll be doing is consolidating things he's sort of met or filling smallish gaps, for a bit; you might also consider getting hold of a good book he can look things up in (we have the Usborne Dictionary of Maths, which I recommend). What it does have instead is a very soundly thought through set of paths through the material, so that a mathy child almost doesn't need teaching: DS basically learns by attempting a question which is only a little harder than things he can already do, and figuring it out.
The positives are cost, as I already said, and that it doesn't have a lot of repetition, but still does enough automatic assessment that it doesn't seem to be possible to move on without good understanding (IME - I've read people say that their DC learned to do ALEKS questions without being able to apply the skills elsewhere, but that's opposite to what I've seen with my DS). Three consecutive correct answers to questions on a topic are enough to "get it on the pie" and move on, and assessments both check topics that are already on the pie and explore things that are not yet on the pie, so that one goes on or back depending on whether more review is needed or nearby topics are skippable. It always presents a variety of topics which the child "is ready to learn" so there are lots of choices, which is also good.
I will say that my DS loved ALEKS at first, and then went off it after about 6 months. There were specific reasons for that (he changed course and for a combination of reasons ended up with "too little" on his pie in the new course which led to him having to repeat a lot of stuff he already knew, which was boring) but it also seems to be a common experience with ALEKS. The format does get a bit samey after a while. I bought a year's subscription, and while we've certainly had value out of that by any reasonable measure (DS just finished his third full course in it, and is still determined to do 2 more which will both fit in the year, I think), I would tend to advise buying it not more than 6 months at a time (and less to start with).
You also mentioned times tables as something your DS doesn't know yet. For that, I thoroughly recommend Timez Attack (
http://www.bigbrainz.com/ - there's a free version that covers all the tables, and then the paid version adds two other "worlds" to play in).
