After about a dozen unsuccessful e-bay auctions, I walked into my local video store and it was on a table for sale (NEW!) They only had 2, so I asked how they got it -- they said that they can order movies upon request and that they probably had ordered a couple of extras. I don't know how they do this, but without any further hesitation, I paid full retail price ($20 -ish) -- chalk it up to a mother's desperation!
I bought the VHS copy, so I don't know if it's available on DVD, but it's worth calling your local video stores. (The one I went to was a local chain, so you may want to try a larger video store).