Thanks DRJ, I tried your macro, but I could not get it to work. . I dont think I'm using any activeX stuff, but anyway, I'm uploading a sample file of what I have been working on. So if you could give it a look I would appreciated.
This is a basic example, users should only have to click on any of the combo boxes for desired options. All references would be hiden at the REF worksheet. I´m using vlookups link both worksheets, and automatically add the cost of the options.

Thanks!!!