Trading Forum

[RateU]

Maybe it doesn't need many fields?
1. Textbox field for price.
2. Textbox field for short description about the materials (or maybe you can use the default message textarea for this).
3. Use the default subject textbox for the material topic.

So, when the first option applied, your user can write the topic they want to be written in the subject textbox.
Put the price in the price textbox.
And add additional information in the message textarea.

If the second option applied,
The expert write the materials topic in the subject textbox.
Put the price for the materials in the price textbox.
And add additional information about the materials in the message textarea.