The simplest version of fluoro analogues is 4-fluoro amphetamine. It is synthesized quite simply, has a powerful euphoria at a dosage of 300 mg orally. You can also do 4-fluoro methamphetamine, which has even better euphoria
It's pretty well said as I have tried the 4-FA for which the benzaldehyde can be found at prices as low as under 200 euros/kg here in EU. However also take into consideration that 4-chloroamphetamine is such a strong euphorectant that it's main use is as a neurotoxin to kill specifficaly the serotoninergic neurons in culture.
Fluorinated building blocks are considerably more expensive than other halogen containing ones and I'm still puzzled where did chemiolis got his at the price he claims at the end of the video. Cool concept nonetheless.