Although the number of people subscribed to games that charge monthly fees for access continues to grow, we've all heard protests from those that refuse to pay any kind of regular fees to play a video game. Many are accustomed to the traditional retail offerings: buy the box, take it home, and play it forever, or until you get bored of it. By comparison, the $10-$15 per month a lot of MMOGs charge may look rather steep, but are they really a rip-off, or are they good value for your entertainment dollars?

Versus Other Video Games
My experience has been that video games, in general, are among the cheapest forms of entertainment to be found, particularly if you don't take the cost of the hardware into account. On the PC, gamers have quite a few free games to choose from, assuming they have an Internet connection.

Free is a good price, but free games don't always live up to the growing expectations of gamers.
At retail a single-player game can cost anywhere from $20 to $80, and usually provides dozens of hours of entertainment, potentially more if the game can replayed using a different class, faction, or gameplay mode. Even if you play through it only once and it takes 30-40 hours, odds are good that it's costing less than $2 an hour, which is pretty reasonable as far as entertainment goes. Another nice thing about single-player games is that you can revisit them years later without having to worry about whether game servers are still available, or whether anyone is still playing. Of course, if it's a console game, renting is another option that will save a few bucks.

Plenty of online multiplayer games have no access fees, and can provide months or even years of entertainment just for the price of the game itself. Online shooters like Counter-Strike, Battlefield, and Call of Duty are good examples of this, as are online RPGs such as Guild Wars. I know people that have played the same FPS for 4 or 5 years before deciding to move on to something else. They've relatively rare, but their video game hobby is costing them mere pennies, if that, on an hourly basis. Of course, they need an Internet connection, which is an expense that isn't required for single-player gaming.

Subscription-based MMOGs typically sell for between $40 and $60, provide one month of access with the game, and charge $10-$15 per month after that. You won't find many people who play for less than 10 hours a week, so the first month may cost upwards of 1 dollar an hour, but after that they're paying under 50 cents an hour, or a fraction of that if they play more regularly. It's also common for MMOG players to stay with one game for months or even years, rather than buying a new game every month or two, which makes a monthly subscription a bargain in some cases.

from about.com