On several of my custom guns where I didn't want to spend a lot of money on glitz I used the bottom metal from Mark X Interarms Whitworth rifles. They have a push button floor plate release that is both very secure and easy to use. Plus they look really good. Go to Numrich Arms for the one they sell http://www.gunpartscorp.com/catalog/Detail.aspx?pid=881550D&catid=9270 They sell a copy of the 1909 bottom metal for less than $80.
Keith