Ninjaflex is on the rather expensive side - but I've started ordering my filaments from filaments.ca getting their house-brand stuff and it seems to be pretty good quality so far. And their TPU (same stuff Ninjaflex is made from) is only about $20 / KG more than regular PLA (they also resell Ninjaflex, at a cost about $100 / KG more than regular PLA). Makes playing around with flex far more economical - I suspect a spool of TPU will probably be in my next order.
I want to play with the metals and glow-in-the-dark too, but need to order a hardened steel nozzle first.
Nice. I'll check them out, thanks. I have good luck with Makergeeks for ABS/PETG. I haven't tried their other stuff. I made some glow-in-the-dark ABS a while back, it worked pretty well. I didn't print much, so I didn't worry about the nozzle. I plan to get some hardened nozzles next time I order printer parts.