Nissan Di622 or Canon EF 50mm 1.8

Sadly, I just can't afford the Canon 430EX II. Been looking at the Nissan Di622. Been looking at the nifty 50. Here is my question:

Compared to my kit lens the nifty 50can get a lot more light, for primarily indoor shots, would it be an effective substitute for a flash + kit lens?

Or should I just get the NissanDi622 and use the kit lens?

My bug concern is that I don't know squat about flashes, I'd lime to Tetons that I can put on, switch my T2i to Av mode and have work 100%. Will the Di622do this As always,I really appreciate the feedback. Funds are tight.