Using this plugin you can perform mathematical operations like Percentage, Multiply, Add, Subtract custom filed value with main products. For example: If your main product is Business Card & Standard price is $10. But in your custom field you want to put 2 sided color option & that will be 20% extra of main price. With this extension you can do this easily :).
Follow this procedure:
> Download the plugin & install that using Joomla extension manager.
> Now go to "Plug-in Manager" & Search for " VMCustom - Custom Price Based on Mathmatical Sign" & published that.
> Now go to "Custom Field" menu from virtuemart & Click on "New" button from top.
> Now select "Plug-ins" from "Custom Field Type " & put anything "Title" in title. Now very bottom choose "VMCustom - Custom Price Based on Mathmatical Sign" from "Select a plug-in ".
> There you will see 2 text field "" & "Options" . Put Title like: Special or color etc & in "Option" put the necessary option separated by comma(,) like: 2 sided color, advance color etc.
> Now Go to products menu from virtuemart & open existing products or create new one. From product edit area click on "Custom Fields" tab & choose custom field title that you just created :) from "Custom Field Type" drop down.
> You can see that 2 fields with name "Custom Field Based on Math Sign". In "Selections seperated by comma. " filed input will like this:
OptionName|MathSign MathNumer,OptionName|MathSign MathNumer
For example: My Option name: 2 sided color
Math Sign: +%
MathNumer: 20 (because I want to add 20% extra price with main product)
2 sided colo|+%20
again for special color: +30%
So I will put in "Selections seperated by comma. " like this:
2 sided colo|+%20,special colo|+%30
If you don't want to increase price then put simple option name like
1 sided color,2 sided colo|+%20,special colo|+%30
Supported Math Signs are:
Percentage: +% or -%
Multiply: * (this sign can put from your keyboard number 8 button)
subtract : -