Trans fluid $$$???

Type F is about $6. at Walmart.
Does anyone know where to buy it cheaper?
We have 10 race cars all with aluminum speciality
internal Drums etc. and need to change them all every
20 runs to get the aluminum flakes out.
The brand does not seem to make any difference anymore!
Rural king used to be $3.99 a quart for type f. It since has gone up to $5.49 a quart. That is what I use in my race transmission as well as other race transmissions I build. I’ve gone many rounds with it and it treats me the same as every other type f I’ve put in.