November (late October)to February are the best times to visit most parts of India, except Kashmir and other laces in the mountains. If you like to be there for the Holiday (Hindu/Muslim) season Oct/Nov is good. Avoid monsoon season, which roughly covers June to August. Monsoon arrives earlier in the south than in the north. In the northern planes, it's already hot in April. Between May and early July, avoid popular "hill stations" in the north, which are now crowded, filthy tourist traps. We can provide you more information once we know which part of India you intend to visit. If you are going to Bombay, Dec. to Feb. is good. as Bombay winters are warmer than fall in mid Atlantic states.
Tickets should cost between $900 and $1600 in coach depending on the traveling season. Fares would be towards the lower end between Nov and May/June except Dec 10 to Dec 25th and the first week of January. Availability, at its worst in December, can be bad on certain dates (Holidays) in Oct and Nov also.