I have a project where my client wants to create a "shopping basket" for features, where respondents will check a list of features in a check box that they want, and each item is associated with a cost, thus the running total appears at the bottom of the page. Furthermore, some checks will be dependent on others, so they'd like a warning message to pop up if they check something like "rear camera" without checking a screen mounted on the dashboard. Not exactly sure where to start with this one... I'm assuming creating a free-format question but aside from that I'm a little in the dark. Any help would be very much appreciated!