Creating a button, giving it a delegate (or Action), and giving that delegate a reference parameter

Hi. I've created a bunch of static functions to help me set up UI elements when I need them, things like initialising a build-units menu or a resources graph (this is for a strategy game). I've been using delegates and Actions to allow me to hand the button initialiser a function to subscribe to the button's onClick event. So far, this has worked fine. However, when I have a text field that can change its text value - for example, an input number for how many items the player wants to buy - the delegate doesn't take a reference. So if I open a menu, the menu's input field will be 0.0, and call the function Buy(0.0f). But if I change the value in the input field to 3.0, the button still calls Buy(0.0f), because that's what the value was when it was created.

Strangely, though, I wasn't having this problem until recently. See, my normal Button-with-an-Input-Field prefab has a Button, and an Input Field childed to that Button. From what I can tell, this means the Button can handle the Field's text as a reference, since it always knows where the Input Field is. Here's the function for creating a FieldButton:

 // Function to quickly set up a numeric field button.
     // This accomodates a function with a single float parameter.
     public delegate void floatDel(float f);
     public static GameObject InitFieldButton(Transform parent, Vector3 position, string text, floatDel function)
     {
         GameObject newElement = GameObject.Instantiate(fieldButton);
         // Establish UI transform data.
         newElement.transform.SetParent(parent);
         newElement.transform.localPosition = position;
         newElement.transform.GetChild(0).GetComponent<Text>().text = text;
 
         // Assign the argued function to the button, with the input text as a parameter to that function.
         newElement.GetComponent<Button>().onClick.AddListener(delegate { function(float.Parse(newElement.GetComponentInChildren<InputField>().text)); });
         return newElement;
     }

This works. If I change the value in my input field, the button will call the function with the updated value.

But I'm also using a whole bunch of buttons that reference ONE input field, for when I want to let the player buy lots of different things, but only need to specify one quantity. This is obviously two prefabs: a Button, and an InputField. So I'm doing exactly the same thing with my InitButton() function:

  // This overload accomodates a function with two parameters: a trading good, and a quantity to be traded.
     public delegate void purchaseDel(Good g, float f);
     public static GameObject InitButton(Transform parent, Vector3 position, string text, purchaseDel function, Good good, GameObject inputField)
     {
         GameObject newElement = GameObject.Instantiate(button);
         // Establish UI transform data.
         newElement.transform.SetParent(parent);
         newElement.transform.localPosition = position;
         newElement.GetComponentInChildren<Text>().text = text;
 
         // Assign the function delegated to this button.
         newElement.GetComponent<Button>().onClick.AddListener(delegate { function(good, float.Parse(inputField.GetComponent<InputField>().text)); });
         return newElement;
     }

I've tried quite a few things. Using 'ref' doesn't seem to be an option, because anonymous functions such as the one I'm handing to onClick can't take refs. I'm currently looking at giving the button a custom script to store all the data I need, but I expect this will be messy and really non-generic.

This seems like a pretty common thing to want to do. Is there a better way?