Surely the pursuit of culinary authenticity would require you to fly out to Rajasthan in advance of your kitchen escapades to harvest any spices yourself (ensure you dry them in the tropical sun, any other sun is insufficient) and get a holy man to roast them (adds to the flavour). Only then can you fly home, on the eve of your meal, clutching your spices. Once home resist the urge to grind your spices until no more than five seconds before you put them in the pan and then only grind with genuine Himalayan stones.
It still, of course, won't taste the same as they have different gravity in India.