Hi guys, I'm not really good in web design nor html so I try to get a book to learn more about it. I come accross a website that sell book. The weird thing about this site is that the book has different prices when using different computer to look for it.
I try check up a book "Creating Web Pages for Dummies" and the prices on my laptop and desktop of that same book is different.Also I search a couple other book and some of them also have different prices between my desktop and laptop.

My question is how is that possible, my understanding is that a website would store prices on their own database so that people can't mess with the price. How is it that in this case the website would give different price for the book when using different computer.

Professional sites will do that. For example, you aren't going to catch websites for companies like best buy or online businesses such as Amazon that don't check the price against their database when you buy an item. But if you are using a program such as Firebug, I think you can capture and edit web pages - so basically, if you were on a website and were purchasing an item, you could edit the price of the item and then buy it, assuming they did not check to see if the price matched on the server side. I know that is a little off topic from what you were saying, but it is a concern. And illegal to do, obviously.

http://getfirebug.com/

I don't personally use firebug but there's the link to the tool I was talking about.

Oh, and as for your original question, it could be the website doing it I suppose - if they had some way to detect the specs or type of your machine. I guess it would be clever to attempt to charge people using higher end machines a higher price for the same item. Dishonest but still. That might not even be possible, I'm just speculating. There could even be a virus, although that would seem very strange and implausible as well. Have you tried looking at the same website on multiple other machines to see what happens?

Thank you for your reply, I remember hearing about edit the webpage to change price in one of the security presentation at school a while back (they said people actually change price to negative and get money back, that was crazy). I assume that all website would not have that problem now, I don't see how any decent programmer would make such a mistake as to not check for illegal edit input.
As for your idea of checking buyer comp spec seem very logical since the price is only couple dollar off. I would check the website again at school and try it on multiple computers lab, I didn't bring my laptop today and I don't remember the website address.
I didn't think such thing was possible, I thought website only store cookies but it seem they can get other hidden information without our knowledge. It was very interesting, thank you for your answer.