You aren't selling preset, prepriced PCs so it won't be cheap. Someone is going to have to do some pretty serious coding to accomplish that for you. If you were just selling PC package A which cost $XXX and PC package B that costs $XXX, it would be cheaper. But I understand that you want to allow them to customize their PC, who wouldn't? That is where you are going to run into $$$$. If you are looking for something like what Gateway or Dell does where you have drop down choices for Processor, Memory, Hard Drive, Monitor, Video Card, Sound Card, Network Card, Monitors, etc you are seriously looking at thousands of dollars for a customized solution. Then, all those prices and part descriptions need to be stored in a database and pulled onto the page to display. I can't even phatom a cheap solution to your needs due to the fact that there is no set price. The price will always be different depending on their needs. I hope that makes sense. Peronally, I hate building those kinds of sites and that is why I am going to back to school to be a Respiratory Therapist. Once people find out how much it is going to cost, the sticker shock kills them and the deal usually. HTH
Technologies that I would employ would be of course, HTML, CSS, JavaScript, some VBScript for the forms, ASP, and run it off an Access Database. Or even do it all in asp.Net?
Hopefully someone will read this and say, screw that, I can do it for cheap. Keep bumping it, there are a lot of smart people who do this for a living on here. Your best bet is to find someone young, green, but very eager to get their name out there who will do it for a song. Good Luck. There are site like eLance and Guru.com where you can find desingers and coders cheap. But more often than not, you get what you pay for. You could always outsource it to Indian developers for maybe $500? I did that once for an online eHarmony type dating site that we had bid for $20.000 US to a UK Dating company. In the end, we ended up just giving it to the Indian Developers to do in PHP for $1000 and kept $19,000. So don't give up hope. Where there is a will there is a way.