You've likely seen the ad that Rapid Flux training is on sale (edit: or seen it mentioned in the The Great Halloween Contest event page) and wondered how much the final cost actually is total. I went and checked myself because it the news posts weren't clear on how much it actually costs (just the discount percent) so I posted it so nobody else has to bother to find out the cost. This might get more expensive if you have absurd number of images or particular settings, but this gives you an idea.
For comparison (since it's also rarely mentioned in training guides), training SD1.5, SDXL, or Pony will cost 500 unless you up the settings or include a lot of images (using the max of 1k images in training will cost just a few hundred extra buzz). Training reasonably sized SD LoRAs takes about an hour (though it make take a few hours to start training if server load is high), but I've got no idea how long (non-rapid) Flux training normally takes (add a comment if you know).
Pic unrelated. It's a random test image. Prompt was "score_8, score_8_up, score_7_up, source_anime BREAK 1girl, female focus, solo, full body, hatsune miku" and it used AutismMix