I have both the kit lens with 3.5-5.6 and 50mm f1.8 for Canon.
50mm@1.8 gives me 6-7 stops advantage in same light situation as compared to my kit lens at 3.5. The shots which i can only take at 1/5sec handheld with kit lens (IS off) are possible with 50mm at 1/20 or 1/25sec (50mm has no IS).
50mm is excellent for indoor and kids in particular as i bought this lens for the sole purpose of taking shots of my kids 
I bought mine 50mm for Canon in Feb 2011 for Rs. 9,600 but that was wholesale rate. Recently, Zaeem89 has purchased the same for Canon and he may be able to confirm the latest retail rates.