I just know that I'm not happy with the results i get from my 55-250!
Maybe you could explain to us why you are not happy with the results from the 55-250? AF too slow, build quality, optical quality? Focal length? Aperture? This would make it easier to recommend something for you.
In general: I have lived quite a long time in India and photographed most corners of the country.
You can check out my pics here if you want: www.photography-in-style.de
In general I am no longer using long white tele lenses in India. The exception being wildlife (esp. tigers) and the occasional compressed landscape.
When I started out I used a 70-200 f/2.8. Then I switched to the 70-200 f/4 IS (w 1.4x converter) because of weight (both on full-frame). In the end I even largely abondend using the latter lens.
The reason why tele lenses have not worked too well for me are the following:
1. too big, too heavy- they wear you down in the heat and keep you from getting shots (Exception, see above).
2. too eye catching in the cities and crowds. People will shy away from your camera more easily while doggy characters are attracted (touts and thieves).
3. It is a hassle to fight through the crowds with such a big lens getting in your and other people's way.
4. your photographs are not very engaging, because you have to stand too far off. Better invest in a good midrange zoom and a nice portrait prime (85mm 1.8, 100/2 or 100/2.8 macro) and get close to your subject
. A UWA lens will also come handy.
5. Unless you shoot wild animals full time, better carry a light, black tele zoom for the rare occasion where you really need it ( like 70-300 IS non-L or Tamron 70-300 VC) This should also do for compressed landscape. The opitical quality of both lenses is very high.
Regarding lens cost:
Prices in India are either the same or slightly more expensive than in Europe (dfepending on the exchange rate). You usally do not find special offers and the shops may not stock your desired lens. Consider also guarantee issues. I have browsed through some stores in delhi (Connaught Place area) and Mumbai(Fort area) and found hardly any L-enses in stock, even in the bigger stores. Probably better to buy at home.