Generally, train tickets are sold only 10 days or so in advance, this is does not give much time to pre-trip planning. Online payment is still a problem in China. As result, people either buy their tickets themselves or through a third party such as a travel agency or a hotel where they stay.

Q: What are the most reliable sites that offer the most competitive rates to book train tickets in China? Also which are the official sites of the railways? Is it cheaper traveling by train than flying budget air lines?

Currently, the purchase of tickets for trains in China cannot be done conveniently. This is due to a number of reasons. Generally, train tickets are sold only 10 days or so in advance, this is does not give much time to pre-trip planning. Also, for most train trips, fares are low and there is not much profit in train-ticket retailing. Finally, online payment is still a problem in China. As result, people either buy their tickets themselves or through a third party such as a travel agency or a hotel where they stay.

One of the larger travel websites in China is ctrip.com. It offers information on train travel but does not provide ticket-purchase service (it does sell plane tickets and hotel rooms). The train schedule it provides, however, is in Chinese and does not seem to be part of its English presentation. Therefore, just drop in an email to your tour operator and I'm sure they will solve these kind of trifles as ease as a piece of cake.   

Usually, people purchase their tickets through a travel agency or a hotel, at train ticketing offices that can offen be found across a city, or at a railway station itself. If possible at all, try to avoid the railway station option, as it can be a rather hectic thing to do. Numerous travel agencies offer train ticket purchase service, but it is hard to say if they're reliable or not. For foreign travelers, working through their hotels seem to be a good way to have this done. Generally, the fee charged for a train ticket is in the range of 30-60 Chinese yuan.

Generally speaking, in China, it is cheaper to travel by train than by plane. A soft sleeper on a fast train may cost as much as a plane ticket, but in most cases, train is a more economical way to travel. For example, whereas a soft sleeper on a fast train from Beijing to Guangzhou costs about 700 Chinese yuan, a plane ticket between the same destinations costs about 1,000 yuan.

There is one notable difference between train tickets and plane tickets in China. Whereas prices of train tickets remain almost the same, there are often hefty discounts on airfares. This means that you plan right and book your plane tickets at the right time and right place, you can save a little or quite a bit, but this is not true with train tickets.