simple. they were sent RFP's for the contest.
historically western equipments have cost more. no denying that. at the same time they have been qualitatively superior and their support system works better
of course at a cost.
why can't we buy f-16/f-18?? are you referring to the reservations india/iaf has about EUMA restrictions??(i agree there) if yes, that is a different point of debate. the fact that f-16/f-18 are participating in the contest is for the sole reason of selling them!!
what about C-17 purchase via FMS??
let me enumerate a few points here -
1. wide bodied C-17 allows you take in a tank (be it Arjun or T-90) which a IL-76 can't because of width restrictions. how
important this requirement for IA is not clear.
2. IAF may be needing the transport aircraft urgently based on their assessment wrt their IL 76 fleet and their spares position, their servicing situation and the situation at the OEM's.
3. the cargo carrying capability that a C-17 (75 tons) far exceeds IL 76 (48 tons) meaning low number of sorties for high cargo transport.
how can they compete when they are not even in production??
as for AN-124 here is what wiki says -
http://en.wikipedia.org/wiki/Antonov_An-124#Design_and_development
also sir, IL 476 is yet to fly.
http://www.globalsecurity.org/military/world/russia/il-476.htm
as against these C-17 is up and running and is being flown by mainly NATO countries.
ADDED LATER :
as for the cost of IL 76, the phalcon deal with Israel gives an indication -
http://www.defenseindustrydaily.com/Indian-AWACS-Moving-Forward-on-2-Fronts-04855/
it is clear, 3 IL 76's with PS 90 A 76 engines cost 400 million dollars meaning 133.3 mil $$ each
and not 50 mil as you are quoting.