One way ticket back from Mumbai, for example, is about 10K-11K rupees, on either Jet Airways (not Jetstar, Jet the Indian company), Air India, Thai, or Singapore Airlines. Inclusive of taxes. That's about 400 dollars. It'll definitely be easy to buy a ticket back when you're in India, even if it's last minute. There're travel agents everywhere, and flights everyday!
I think it's the same in Delhi and Allahabad. So the cheapest one way back will be from Kolkata (I believe it's in the range of 8000 to 9000 rupees). I hear it's quite cheap to fly back from the far south (aftere all that's where TT Durai got his SQ tix from!) but I don't think you will be headed there.
So if you add it all up... Singapore-Bangalore via Jetstar is about $200ish usually, incl. taxes. Then add another 400 to come back. Return tickets from Singapore in Dec can cost between $800-1000 because it's high season. By doing what I suggested, what you're actually buying is the flexibility of not having to loop back to any place in particular (trust me it can be quite hard to get train tickets on the days you want during the season), which can waste a lot of time and effort. Buying a open-jaw ticket from Singapore (flying into one place and flying out of another) is also quite expensive. But if you want to find out about airfares to India on conventional airlines, try calling Mustafa Travels (at Mustafa Centre), Ramesh Travels (Peninsula), or International Indenting House. These are the agencies that most of my Indian national friends use.
Jodhpur is nice... but it's really just a big city in that part of Rajasthan. That sort of architecture is found throughout all of Rajasthan, with the old
havelis and all. Jaisalmer, for example, is really spectacular. It's a desert city, and you can go out into the desert, living inside the Jaisalmer Fort is really special. I have also heard good things about Ajmer. I think it's inevitable that you will pass through Jodhpur at some point, for transport connections if you're in the area, but in terms of the awe factor that Rajasthan can have, it doesn't have as much as the other places. (Jaipur is Pink City and Jodhpur is Blue City... I don't remember seeing so much blue in Jodhpur though!) Udaipur is really beautiful. If you're still keen on going to Jodhpur I can recommend you fantastic guesthouse (with AC and toilet and really nice furnishing), with a good host. Think I only paid $14 for it. The highlight of Jodhpur for me was the food.. the hotel owner drew us a little map of local food, and we went around drinking THE BEST LASSI (I drank it 4 times a day) in the world for 50 cents, wonderful samosas for 20 cents, and really really good Indian ice creams for 20 cents.
For some photos of Jaisalmer, take a look at my
post. I also have a short write up on Jodhpur
here.
From your posts so far it looks like you're magnetically drawn towards Rajasthan... which is really beautiful! Don't know if you can cross into Pakistan from that side, though, you need to go further up to Amritsar I think. How long do you have to travel for? It's a really long way from Bangalore, unless you're going to fly domestically.
Cost-wise, I spent less than $2000 for nearly 2 months in India (incl. my airfare). I travelled entirely by trains (AC class with beds) and buses, slept in nice-ish hotels, ate good food. A lot of people I know can spend half of what I spent... and get by
However, you have to keep in mind that Nov/Dec is going to be more expensive. A hotel I paid 400Rs for, for example, is going to cost you 1500Rs.