I dont talk much about avionics/ design etcs as we are not in this profession but a logical argument says, if IAF is happy with paying $3.9bn to upgrade their 51 Mirage2000 to 2000-5mk2 standard, and its manufacturers now closed its production lines when they started producing Rafale with a claim that Rafale is more capable for a2b operations with a very capable a2a role also than mirage2000-5 mk2, then obviously Rafale is worth paying $100 each + establishing infrastructure cost also
I have read on few places that even if F35 is a complete 5th gen stealth aircraft, Rafale will be able to dodge its all the missiles but if Rafale will have got F35 on its target, F35/ JSF is not capable enough to dodge any missile of Rafale (or of SU35/ SU30MKI also). IAF is not only negotiating for stealth features with Rafale, similar to SU35BM, but also Rafale is already capable enough to deal with of any 5th gen aircrafts even in a2a combat while Rafale is said to be the best Multi Role Aircraft, primarily for a2g operations
see the condition of the US's best JSF, the 5th gen aircraft, and Australian scientists finally selected Rafale with JSF/F35 over rest of the aircrafts. Rafale is already put in the category of US's latest and best F35/ JSF