Not a bad suggestion by, you can start IHP customization shop.

Other i was talking to my bad, he said that there is Co by the name of Springindia, which is pioneer in india for Spring manufacturing. I googled for that guss what, that Co is still there
http://www.springsindia.com/
I was thinking of contacting them with the spring details and ask them if they can produce it.

Wild guss but may fellow IFG can get together and may be we can give them order of something 5-10 spring, with the specs created by all the air gun gurus.
Coz if it works i think it cost fraction of JM spring, that spring is cost around $20=Rs1000/

and Original IHP spring is costing Rs200/

- So my guss is that we should be able to get very good spring around 750-1000, but atleast there will be no Import headache from US.
How does it sound.