Use a Token in Minimum Field
In a nutshell, there is no way that I know to do this with a token. You need to create a custom module that implements hook_form_alter() to set the default value of your minimum deposit field before the form is rendered. You'll set this default value using the value of the field in the pre-existing node (you'll need to load the node programmatically within the hook function and get the value of the field).

I could give you more details if you let me know what type of form you are using: are you creating a form programmatically with Form API? Using Entityform module to create the form? Using Webform module? Using the "Add to Cart" form provided by the module Drupal Commerce? Post a comment below and I'll edit this answer.