The prices for train travel vary depending on the destination and the time of the year traveling. I suggest watching the rates and finding a less popular time.
There is no airline that provides the cheapest travel for business trips. The prices fluctuate daily and most airlines have similar prices. The prices will depend on the day you are traveling, the number of stopovers, and where you are going.
The cheapest luxury train in India is the Garib Rath.
traveling by train advantages and disadvantages
It is difficult to determine which airline has the cheapest prices on average because prices are constantly changing and it can vary greatly depending on where one is traveling and the time of year. There are however websites that can assist in the search for the cheapest flight by comparing prices from all airlines. Websites such as FareCompare searches all major airlines for the cheapest price.
You may want to invest some of your searching time in a traveling agency office, they can usually get you hidden discounts and the cheapest prices. Online sites, such as Expedia also claim to offer the cheapest airfare tickets.
Costco has the cheapest prices on gas.
Walmart
train
puppys
Walmart.com seems to have the cheapest prices on dry erase boards. They have various sizes and prices to choose from.
Discount Airlines such as Spirit will offer cheap airfare, however they provide those prices by un-bundling all their services. For instance, there's a charge for carry-on, to select seats in advance, for blankets, etc. Jet Blue and Southwest offer great discounts w/o compromising quality.
Cheapest and Quickest, is by train.