Anybody know of costs involved? My web travelsite quotes over $350U.S. That seems steep. What are the cheaper(?) local airlines that do popular routes?
Thanks!

Kingfisher is not a budget airline. Budget airlines include Go Air, Indigo, Air Deccan, SpiceJet and arguably Air Sahara. Legacy carriers are Air India, Jet Airways and Kingfisher.
Provided you buy your tickets a month or so in advance you can fly Delhi-Mumbai (one way) for INR 1725 (USD 39) with Indigo, INR 1958 (USD 44) with Air Sahara or INR 2124 (USD 48) with SpiceJet (all incl. tax). Of the three I believe only SpiceJet accepts international credit cards on their website.
Source: yatra.com