Amount & Cashout

This is for my 4 websites. [login to view URL] [login to view URL] [login to view URL] and [login to view URL] I would like to add a new system to the members area where they can choose how much they want to cashout but to also put a limit to minimum $300.00 per cashout. Maybe a box which will appear asking the member how much they want to cashout? Any other ideas, let me know. I need this urgently! I want the job professionally done. Thank you, Rodney