When I started out homeschooling, I wanted to do as much as possible in the younger grades on a really tight budget. For math, I grabbed a Spectrum math book at Barnes and Noble using my educator's card for under 9 bucks. Then I used it as a skeleton for our year and added worksheets to each unit from printing out freebies. Spectrum has since gone common core as have most of the workbooks at the bookstore so I found a great alternate site that could make a very effective outline. It's called Math Drills and there are a set amount of pages for each skill. If you scroll down the page, you can see the main listing of skills and you can start with early skills like learning numbers under the number sense banner and go up from there. The only drawback is that the listing down below is alphabetical order and not by age/skill level, but only a little organization is needed to get around the sites. The other benefit to the site is that once you get to the page with the sheets, you can download the pages one at a time or in a mass pdf. This makes it much more easy to print the pages and assemble them into a binder to make your own workbook that is similar (if not better) to the common core ones on the shelves.
Once you have your basic pages printed and assembled, you can work through it with your child and go to the other free sites to print supplemental sheets as needed for you kid. There are two basic styles of math learning--spiral based and mastery based--and this create your own workbook method could work for either. Mastery focuses on learning a skill throughly before moving to the next topic. If you opt for mastery, you could use just the pages from Math Drills and add as needed from other sites until each skill is mastered. For example, if you kid learns numbers quickly and breezes through addition but gets stuck on subtraction, you can print extras of subtraction to insert before you tackle the time pages. Spiral math is heavy on reviewing topics as you go, so you can arrange the pages in your binder with the supplemental sheets scattered throughout the notebook and add sheets on weaker areas.
Overall, I'm glad that I found this site that could work as a solution for the common core workbook problem. I actually wish that I had known about this site before we finished first grade because I could have done a much better job tailoring his first year of math to his skill levels.