I havent ever bought a font, nor came across anyone selling fonts, but i have nothing against people buying them or indeed selling them. If you had a unique font for your website, then it would make it a bit more different from the others.
It is not really needed to buy fonts, as you can either make your own or just use some free ones. Basically you can change the font, simply by adding various types of effects and it depends for what exactly you are using them.
There are far too many excellent free fonts available so selling generic fonts is likely not a good business model. If you sell a service that will create a font from scratch you might have more luck but the downside is that browsers may not be able to display them so your business is limited.
F.Y.I. in HTML 5 you can use CSS to create custom fonts, it's a huge step forward for CSS abilities, check it out.
I think I purchased a pixel font like 10+ years ago, but it was only a few bucks. If I was running a larger design service, I would probably pick up a copy of Adobe FontFolio along with the other products in the Adobe Suite. Font Folio contains a lot of the most popular commercial fonts.
The one reason you would need some of these commercial fonts is if you are doing work for a client who has materials that currently use them. In other words, if certain commercial fonts are part of their logo and branding, you need these on your system as well to continue working on graphics and other stuff for them.
Unless you are seeking out a very specific design or a font to go with a theme, or even one to go with a web application or game, it is unnecessary to pay for fonts. Furthermore, if you really need fonts for this purpose, it's better to create these fonts yourself in an application like Illustrator, and then add them as pictures with descriptions of text and whatnot to your website for SEO. We're not all adequate at graphic design, so you might look into paying for fonts to work with as a base or by themselves. For me, it isn't worth it.
I had once asked my client to buy the Helvetica font as he needed it for his site. I don't remember how much the client paid for it. If my client needs a particular font or even a graphic image, then I ask them whether they would buy it directly or whether I should buy and then invoice them. I prefer my clients to purchase all the extra items though.
I think that if you want a look for your product, but a font. It would put you out of your competitors. There's also supporting a certain group who creates fonts. There are also thousands of free fonts out there if you merely need some font to use.
I don't see a need to buy fonts. Most fonts are available for free, and are easily readable. Any of the fonts that you could pay for would really need to stand out, but for a font to really stand out, it has to look odd. This causes the web page you design to be hard to read for the user, while still "standing out". So free fonts will generally be fine for making web pages, and I don't see the point of paying for something that is given to you for free.
I don't think they're worth it, as people said, you can get loads of free ones online. Although, if fonts costs, they are most likely to be really professional ones, but then again, free ones contain lots of good ones. Just a waste of money to spend money on something you can get for free, nearer to the quality.
I have never and will never pay for fonts. I've seen sites that offer them for sale and sometime not cheap. If you you spend time searching around you can usually find the same ones for free elsewhere. If I couldn't find what I needed for free, I would simply use a different font. My answer is to never pay for fonts!