You can do that in 3 different ways.
The first one is the natural way... just enter in the component options (Certificates amounts)
50|Thai Massage 1 - 30Mins, 80|Thai Massage 1 - 60Mins, 120|Thai Massage 2 - 60Mins, 210|Thai Massage 2 - 120Mins.
If you really want to group the price, you can do it BUT those are not natural to the component and not natural to the dropdown menu. You need to modify some HTML.
The easy method is to modify the current dropdown menu, it's pure HTML, now the menu is generated dynamic from the database.
BUT you can remove the dynamic stuff and hardcode what you want, just keep how I pass the value for each massage.
To do that open this file
the dropdown start at line 73 to 104
You can delete those lines and replace it by it's HTML, like that
Now you just need to do the grouping thing in the select (I know you can to that , but don;t know how) Just keep how the VALUE is formated.
The third method is like the link I send you in my last POST here, http://www.polarbearsclub.ca/en/gift.html
With the component you can create single cards with one price and one image (card).
Don't forget when you see a web page in your browser, you have pure HTML in the view source, you can copy the url I use to open the popup
and use the url in a normal Joomla content page.
You can design a nice page with different images and you link them to the component using the url, just change the image name and the price (always keep the same format for the price)
I think it's everything...
BUT the best do the natural way, it's simpler and work great (first example) for the other two you need some HTML knowledge