I don't think LCA will cost USD21 million. I think the wiki has not updated on the price for long..I don't think HAL Tejas is doing too bad.
10 planes are flying in the air. (No crash at all, thus far).
Tejas proved successful on all tests (except for engine thrust required at sea-level - which is why a larger engine is sought). AoA upto 22-24 degrees is done successfully. AoA of 28 degress is under testing.
In case of a blockade from US for GE engines, Kaveri could still potentially be used on Tejas. (Similar to China, which has problems with WS10A in it's process of replacing Russian AL31FN engines for J-10 -- WS10A offers a safeguard to China, vis-a-vis Russia).
True, Tejas has to compete against other western fighters. China's J-10 has no competition from western fighters, which are not offered. Hence, J-10 is an obvious choice for PLAAF, good or bad.
But Tejas is not going too badly against those western fighters .... in terms of cost atleast. Tejas costs USD 21M against Super Hornet F-18 which costs USD 58M.
So, roughly 3 Tejas = 1 Super Hornet F-18.
Tejas is indeed meant to solve the numbers problem for IAF. Mig-21 will be replaced in bulk over the next 5-8 years.
J-10 is a good output from China .. in that it's the only 4th gen plane China has put up in the air (even though, it uses a Russian engine as it's most reliable powerplant).
Both India and China do need western technology inputs.. rather than try to re-invent the wheel. Eventually, both will make planes which are comparable to western planes.
But, it's also possible by the time India / China produce western standard planes .. those planes would cost similar to western planes.
So, as we improve the capability .... cost-wise the new planes won't come cheap.
(J-10 costs USD 28 million; HAL Tejas costs USD 21 Million) as per wikipedia.