Is Indian food more expensive to prepare than Chinese food?

Near as I can tell, it's probably the local economics. It seems to me that the cost is different per "component" but would probably balance out in the end.

Chinese food, generally speaking, relies more on fresh vegetables (carrots, peas, bean-sprouts, broccoli etc.) and meat. This means that the storage costs and spoilage costs are higher relative to Indian food, which is higher in legumes and beans that are much easier and cheaper to store, and last forever when dry.

On the other hand, Chinese is generally quicker to prepare (think stir fry, though not only), which means less time on the fire, and less man-power used. Indian food usually requires more cooking time, which may mean that the restaurant has a larger capital outlay for stove space.

Aside from that, in my experience at least, Indian is usually a register above Chinese for "comparable" places. The Indian equivalent of a Chinese place serving simple rice and 10-12 stir-fry dishes would be a simple Thali bar, but there aren't many of those, as us Westerners like to order several different meat/vegetable main dishes at a time, as opposed to a set menu.

Anyway, note that I haven't done any proper costing of these type of food preparation.

I think Carmi's answer is a pretty good theory for the differences between Indian and Chinese restaurants. It makes sense to me that labor- and time-intensive Indian cooking makes Indian restaurants more expensive than quick-cooking Chinese ones. To add on to that, I'm wondering if the number of different spices and their costs plays a role, too.

Like Carmi, I haven't done any proper cost comparisons between the two, but I do cook a decent amount of Indian food. In my experiences, Indian dishes require a larger number of spices than many Chinese dishes do, and those spices tend to be more expensive. For example, an Indian curry might include cumin, coriander, turmeric, asafoetida, garlic, chiles, cilantro, nuts (almond or cashew) AND ginger. Having to purchase all thoses spices costs me a lot more than making a Chinese dish with a pre-made 5-spice powder combined with soy sauce.

Some Indian food requires spices that are pretty expensive to get (at least in the US): saffron, fenugreek and cardamom, for example, are pricey. You don't typically see those in Chinese cooking, but they appear fairly regularly in Indian food.

All of that being said, I do think that local economies play a large role. There are Chinese restaurants everywhere in New York City, but Indian restaurants are less common and more expensive. However, where I grew up in Massachusetts, there were almost as many Indian restaurants as Chinese, and I can get lunch at a new Indian place there for less than $5. Not sure there is a definitive answer for your question.

'fast food' chinese contains a lot of cheap beansprouts and noodles or rice. Even take away indian contains a lot more sauce and meat.

I always wonder this. A similar takeaway from the Indian will usually be 50% more expensive.

To be honest, I think the fresh fruit and veg is dearer in Chinese food than the potatoes and spinach in Indian. Indian venues use very little variety in way of healthy vegetables.
As for saying the Indian meats take a longer time to cook you are looking unfairly. I believe tikka is done and put aside them mainly added to bought in sauces later.
Think about Chinese foods such as twice cooked pork. It is braised slowly as part of the dish.
The Chinese use a lot of spring onions, ginger, garlic and other ingredients that are so similar to Indian food. To be honest, I think Indian restaurants just price up to a point where people would stop buying, and the Chinese charge reasonably.