Goal Seek Macro

Hi,

I have a financial appraisal in excel and have set up a macro (and linked to a button) so the goal seek function targets a return (in my case 14%) by changing the starting price. However I want the user to enter his/her required return and then by pressing the button the macro changes the starting price. In the macro below how can I make the goal seek which currently =0.14 be a figure entered by the user? Is there a way to tell the macro this figure will be manually entered by the person using the model?

Thanks

Sub IRRproject()
'
' IRRproject Macro
' IRR Target
'
' Keyboard Shortcut: Ctrl+Shift+R
'
Range("E28").GoalSeek Goal:=0.14, ChangingCell:=Range("E24")
End Sub