This is the best thread I found for this topic:
India Buys 8 P-8s for maritime patrol at a cost of $2.1 billion
In terms of the contract size, the P-8I deal supplants the $962 million deal signed with US in 2007 for six C-130J `Super Hercules' aircraft for Indian special forces.
India will get the first P-8I towards end-2012 or early-2013, with the other seven following in a phased manner by 2015-2016. The contract also provides an option for India to order four to eight more such planes.
Armed with torpedoes, depth bombs and Harpoon anti-ship missiles, the P-8I will also be capable of anti-submarine warfare and anti-surface warfare. They will replace the eight ageing and fuel-guzzling Russian Tupolev-142M turboprops currently being operated by Navy.
The P-8I planes will help in plugging the existing voids in Navy's maritime snooping capabilities, having as they will an operating range of over 600 nautical miles, with `5.5 hours on station'.
Customised for India and based on the Boeing 737 commercial airliner, the P-8I will actually be a variant of the P-8A Poseidon multi-mission maritime aircraft currently being developed for US Navy, which has ordered 108 of them to replace its P-3C Orion fleet. India, of course, remains unhappy over the US decision to sell more P-3C Orions, armed with Harpoon missiles, to Pakistan.
At present, the Navy uses the TU-142Ms, IL-38SDs and Dorniers for surveillance operations in the Indian Ocean region. It is also now in the hunt for six advanced medium-range maritime reconnaissance planes, for around Rs 1,600 crore, to further boost its snooping capabilities.
For innermost layer surveillance, up to 200 nautical miles, Navy is going in for two more Israeli Heron UAVs (unmanned aerial vehicles), with three ground control stations and two ship control stations, for Rs 386 crore after successfully deploying eight Searcher-II and four Heron UAVs. There is also the Rs 1,163 crore joint Indo-Israeli project for developing rotary-wing UAVs for use from warships.
Of course this does not mention that the Tu-142 does low-and-slow quite well, and that it has a time of 16 hours on station and can fly to Johannesburg from Bombay without refuelling!
That said, they (and even the upgraded Il-38 Mays) are getting seriously long in the tooth and are (like any Russian system from that time) maintenance-heavy. I love the Bear (and am not really convinced about the Poseidon) but it is way too old.
(Note: 1 'crore' or 'karod' is a subcontinent number that equals 10 million, one 'lakh' or lac is 100,000. Also, As of today 70 Rupees = 1 British Pound while 48 Rupees = 1 US Dollar)