soooo I gave it a try and I gotta say I'm very surprised with the results
first I think it's great for press molds but I'm sure how well it will work with 2 part molds.
you kind of have to feel out how much corn starch you add to the mix, but the mold sets up pretty quick, its stable and flexible but parts that are thick I think will take longer to cure.
I used a 2 part Alumilite casting resin to cast the pieces which had no problem popping out of the mold.
I think it might not capture the details in a 25MM figure but it should work great for scenery pieces.
as for the cost
corn starch: $1.29
silicone: $3.49
Baby oil: $1.99
there is alot of corn starch and baby oil left over so to create another mold would require more silicone.