So let's propose an imaginary scenario....
A customer calls my shop looking for some graphics for an upcoming art exhibit. Let's say it's the gallery director calling and she/he is new to the job and not sure what type of product they need. All they know is they need something for the title of the art exhibit to be installed on the wall near the entry, they also need some kind of labels for each individual piece of artwork (let's say quantity of (30) all with different content based on the artworks), and then they need something to go on the building exterior to advertise the exhibit. So in all there are basically 3 types of items they need. I will offer them the three levels of "budget" or "quality", educate about the pros/cons of each option and then let them choose. So for example item 1 is the title....I'll offer 3 options for this....first is simple one color, cut vinyl to be installed by the customer (this is the "cheap" option)....second I'll offer a direct printed panel of 3mm PVC and offer to add some design elements to it (borders, graphics, etc, whatever is appropriate...this is the "regular" option)....third I'll offer contour cut dimensional letters with vinyl overlay on the face, or if they prefer brushed metal then I'll offer something from Gemini. I have samples of each product type readily available for the customer to see or to save them the trip I'll send them photos of each product. I'll do something similar for the second item in their needs list (labels for the artwork). The "cheap" option in that case might be direct printed 3mm PVC, the "regular" option might be direct printed 3mm PVC but mounted with standoffs, then the "high end" option might be 3mm clear acrylic with second surface direct print and backed up with white again mounted using standoffs. And for their last need (exterior advertising) I might offer a vinyl banner for the "cheap" option, an ACM sign for the "regular" option, and an LED backlit for the "high end" option.
Keeping in mind this is a theoretical scenario meant to explain myself and ultimately answer your question about the price difference. Rarely would an art exhibit call for an LED backlit, but you get the idea. So back to your question about the price difference...this is something that would depend on your/my specific pricing structure, who you are competing with, location, business plan, and so on. So I'm not going to start throwing numbers around but cut vinyl is going to be cheaper than a printed PVC panel which will in turn be cheaper than dimensional letters, regardless of your shop specifics those are basic truths in this industry. And so in a situation like this maybe the customer would go "cheap" with the vinyl title because they don't need anything more and don't want to detract from the artwork with an over designed PVC panel, but in the same breath they might go "high end" with the labels for the artwork, and go "regular" with the exterior sign. while they work out what fits in their budget or not. It only takes minutes or a single email to educate the customer on the pros/cons of each option and then let them mix/match as they please. And puts you in a position where if they don't like the look of one of the "cheap" options that THEY chose you can respond by letting them know that you offered other, perhaps more elegant, options. And they are less likely to pass blame onto you and your shop if someone happens to be unsatisfied with the graphics. So the difference in price has more to do with the perceived "quality" of a given process/material as compared to any other process/material i.e. cut vinyl isn't as high "quality" as dimensional lettering. Hope it helps