Some things we purchased for Evan for school next year....
I know these aren't exactly Montessori, but I think they will be fun and educational just the same. I think, too, that a lot of what he gets out of this will be directly related to the one on one attention. Other than the hammer pounding pegs set, I plan on working with him every time he uses these.
Also, I don't know if I mentioned this or not, but a good friend of mine suggested that those of us in our co-op with toddlers and preschoolers get together and exchange activity bags. We can make 20 of the same activity and exchange them. This is such a good way to give our little ones something to do (other than TV or videos) while we work with our older children. So between spending some one on one quality time with Evan and having a fun bag to give him to occupy himself, things should run smoother next school year.
Don't worry. I'm not delusional. I know there will be days where he wants nothing but me. And that's ok, too.