Our price affecting variants only offer dropdowns, not text fields. However, you can still achieve what you want by using "non price affecting" variants for color dropdown and slogan textbox, and then create two "price affecting variants" which will have an option of "needs slogan" with a value of yes and no.
If you hire a web developer, s/he can also help you disable/enable the text field based on the option selected in "needs slogan" dropdown.
