I also like the Crinkleroot series for science readers.
How about the Montessori Parts of a _____ Puzzles, continent puzzles, and geometric shapes insets? They rock, kids can't resist them. Plus they can be pricey, so having a budget that doesn't come out of your pocket could make them affordable.
Oooh, and as far as Montessori stuff goes, the "language objects" sets from Montessori Services are a super-cool way to work on beginning and ending sounds---the kid gets to play with tiny toys and group them or match them via their phonetic sound, so you have a "p" card or whatever, and she places the "pig", the "pan", the "poodle" etc. in that spot. I think it's awesome. I want them even though dd is probably past that point in the reading.
Also via montessori, the "Child Sized Masterpieces" is a progressive series to learn about art history. What I like about the M. work is that to a kid it's like a game---match the two "Van Gogh Sunflowers" pictures, then it progresses to group all the Van Gogh still lifes then it progresses to group early expressionist works or whatever. Not just Van Gogh of course but you get the idea.
Moveable alphabet. Sandpaper letters?
How 'bout pattern blocks and pattern block cards?
Lots of hands-on materials if they will allow it (my charter school does).
**oh, and Miquon is cheap (leaving you more $ for all those pricey Montessori materials
), plus you can get all kinds of other activity books that use the Cuisenaire rods; just search the ETA Cuisenaire site or Amazon--there are Cuisenaire puzzle activities, fractions, even Cuisenaire alphabet books. The cuisenaire rods rock! I would get 2 beginner sets of the wooden ones as they tend to go the way of refrigerator magnets and matching socks and thus we are short some of the rods at times for activities.