Drop an e-mail to Freestyle, or better yet call them, and I am sure they will get back to you with the answer.
They might tell you when you call that whatever comes in the boxes is simply relabeled such-and-such from some other manufacturer. It may be that the Supreme comes from a constant source, or maybe was actually commissioned by Freestyle, like some of the higher end Arista products; and perhaps the plain-ol' APH periodically changes in source, like with most lower-end Arista products such as EDU. That is just one guess, though. I have no evidence to support it.
At any rate, I have used both of them to make enlarged contact negs and cannot recall the difference, if any.
Also, that quote of $10.99 for 25 sheets of 4x5 sounds off from what I remember. About two months ago I bought a box of 50 APHS 4x5 off the shelf for $12.99.
One way to save money, if going first to interpos. and then back to neg., is to make the interpos. on 4x5, and then project that in an enlarger to get your enlarged negative, instead of via contact with an enlarged interpos. You use half as much of the big film that way.
Now that I look, I can't even find any APH on their Website. It's all APHS.
For continuous tone, I use *one-shot* highly diluted Ilford HC (start at 1:64, which is my normal camera film dilution, and change dilution and developing time to achieve the desired contrast). I have also experimented with the LC-1 formula which I got from pg. 45-47 of the Christopher James book. It offers great control for more precise applications, but is a little more complex to make and use. To make it, you need: metol, hydroquinone, sodium sulfite, sodium disulfite (usually sold as the older name sodium *BI*sulfite at most photographic chemical suppliers), and, of course, distilled water.