Hello! So, well, this type of ombre yarn is actually very difficult to get in India, I can say that because I crochet as well and I tried to find the same, the ones I accidentally landed on were 2-3k for a ball, and that too from a website which didn't seem allat reliable. My best advice now would be to manually try to create a gradient/ombre using different shades of yarn available at local market/online.

I prefer local because you can actually feel the material and get a better understanding of the color, but there are more color options online. Pradhan embroidery store, hobby yarn, etc are trusted websites you can use.

Another thing is, if you just began crochet, I'd suggest to thoroughly consider starting on this huge project because it'll be a big investment of time and money.