The most common Golden Triangle tour is Delhi-Jaipur-Agra.
Offhand I'd suggest that $1,000 per person should cover it. However, we redeemed Starpoints the entire time so I can't speak to the local hotel markets. All three cities had a wide mix of Western and local brands so I would guess that finding accommodation at any price point would be possible. Our Starwoods were midcategory for points...I'm sure I did a basic confirmation that using points was of reasonable value (e.g., wasn't spending 7,000 points on a $70 room), but I don't recall the details. The hotels themselves were of very high quality for their categories.
I also didn't compare/contrast using a driver vs. internal flights and trains. The research I did suggested that a driver would be (by far) the most efficient way to travel, given that we wanted to visit a few off-the-beaten-path sites. Obviously if the cousin comes along this becomes an easier choice.
Food was inexpensive. Only thing I was a bit surprised at was that I didn't have one meal there that I thought was truly fantastic. I love Indian food as it's prepared and served by Indians in Europe and the U.S., but locally it didn't do as much for me. We had just come from a week in Nepal, where I thought the food was much better. But maybe that's just me...maybe we had bad luck. In any case, Italy would be the foodie tour, not India.
