Talk with your local NH dealer. They might be able to get you a 9XX (914 is current model) belly mower. You will need model specific mounting brackets.
Cost about $2,500.
If that's too rich for you, you could go for a rear mount at about 1/2 the price... or once you have the mounting bracket info, keep an eye on your local classifieds and ebay for a used 914. You might be able to get additional brackets.
The TBN Classifieds section has 2 New Holland MMM's for sale...