Have you done a 'directed search' on eBay for that mold?
If not, then 'WHY NOT!!' I've found many good molds on eBay. 
By the way, that 300 grain .44 mold may be available in a 4-cavity as well as 2-cavity. (look on MidwayUSA.com)
And if that mold was ever previously made by Ideal before Lyman, it may be possible to find it (on rare occassions) in a 1-cavity mold, great for modifying into a "hollow-point" mold (whether for revolvers or rifles! That boolit in a 300grn HP would be formidable as hell from wheelgun or .44 cal rifle; .444Marlin or .445 Super Mags especially).
