Most homes will have coloring pencils or crayons. In my house we also have glitter pens, foam pens and most importantly paints for the kids to select between. Using paints will require a little bit more setup time as you may need to clear an area and lay newspapers down over the table to protect it.
Since everything a toddler does become an invigorating learning experience, the images should definitely be of things that they recall, if they can name it, the better. Toddlers learn better through visual examples and what better way to do this if not with coloring pages. Hence, you can use coloring books to teach more to the toddlers than just colors, you can do the alphabet or count numbers. The alphabet or numbers can also be big enough for the children to do some coloring on them too.
Think of the coloring pages that you do not have to buy for your child. Yes, it is possible if you want to go online search a little for the long list of sites that are offering free online coloring. No more hassle to select the shop, go there and try finding the favorite cartoon character of your child. One, the favorite animated characters are not always available for sale. Sometimes you have to visit more than one shop to find the coloring book of your child's choice. Being a parent you have to find time to buy all the coloring stuff but if you go online there is a treasure of coloring sites that await you. You just have to get them printed