Yes, if you know exactly what you are looking for; it does take some time if you really want to find the best possible deal (which is why travel agents are useful - their databases already have that information on hand) for a specific journey or destination.
It depends, but these days I have found that the airline web fares are often better than what the travel agents offer, and sometimes even lower than Expedia, Kayak or other web travel sites. However, the airline websites may limit your search to their partner airlines, whereas you might get cheaper fares across different airlines for different segments of your trip.
Buying a Louis Vuitton purse online is cheaper.
It is cheaper to buy flights directly through the airline operator. Travel agencies always have extra fees as they do the ordering process for someone who wants a flight.
Cheaper and convenient
Buying ink online can sometimes be the cheaper option compared to buying it in store, however often times shipping will cause the price to be greater than expected when buying online.
The benefits of buying a wireless router online through Amazon is that you don't have to drive or walk to the store. Buying it through Amazon is also in most cases cheaper, the quality of the product can be lower though.
Buying Clinique products online is no different than buying them at the store. However, buying these products online often offers more variety and of course cheaper prices.
I have heard the sooner you buy the tickets in advance the cheaper your can get the tickets. But I do know of a cheap website to buy airline tickets online at: www.orbitz.com.
Buying stock online will typically be cheaper than buying through a broker. Also in some cases online purchasing is closer to real time in the market compared to calling your broker and having them process a transaction.
Kodak USB cables are cheaper online because many of the ones offered are used. You can buy them used from places such as Amazon, and eBay. They are not necessarily cheaper if buying them new.
You can find cheaper jewelry online, but buying online is a gamble. It is much harder to tell if a product is real, and if you are ripped off, it is much harder to return the product and get your money back. Going online has the potential to be cheaper, but buying locally is much safer.
The advantages of buying computer games online are: instant delivery of game, no movement required to get to a store, and online purchases are usually cheaper than physical copies.
There are a number of advantages of making an airline reservation, this include being guaranteed a seat on the plane, being re-seated on another flight if the initial flight is cancelled, as well as not being stranded in a location due to being unable to obtain an adequate flight. It is often cheaper to make a reservation in advance >60 days is best.