photoshop sizing and placement of 64 photos

I need a Photoshop file creating where 64 photos are sized and collated to create a matrix of photographs on one print. Template layout will be 5 rows by 5 columns of photos sized at 6.25cm x 6.25cm. Photos will be provided by email or dropbox If the quality and service is acceptable, I am looking to place many orders for very similar projects on a series of template designs which will be created This is the first of many one off matrix photo prints so I am looking for a supplier who can work quickly and cost efficiently responding to one off orders. The following price Price discounts are required based on number of orders placed : 1 - 10 orders 10-50 orders 50-100 orders 100 orders and above