Thanks for the reply, I'm from Singapore (Southeast Asia). The price increase was by Canon themselves from around US$16 to $24 per cartridge at least. Hence looking at whether the ink cartridges from US is usable as I frequently order film and papers from B&H.
I am using a Pro-300 too and am trying to find out if the printer or cartridges are region coded. The price for OEM inks in my country has recently jumped by 50% and I'm looking at options from B&H.