Do you have a buy/sell homeschool FB group? Or buy from an online used book shop that ships, I have one near me. It's usually not hard to find, I never bought a copy at full price. I used Saxon the first couple years then switched to beast academy. You can take as much time as you like with Saxon, they say you have to do everything but I didn't always. The manipulatives can be whatever you have around the house. A balance scale is not that much and they get a lot of fun out of it. Other than that, I used whatever I had around
I got a little clock at Goodwill, used Legos and stuffed animals and minifigs and beans and hangars and food, whatever I felt would keep their interest.