Average price for a m class fare lhr to New York

Good afternoon everyone. Seen a lot about m class fares on here recently. Looking to use miles for upper class upgrade. I realise I need to have 50,000 miles for the return trip but was just wondering what the average price for an m class fare to New York will be and the cost of additional taxes.

Go here: http://matrix.itasoftware.com/

Put your choices in (use LON & NYC to get all options), click "Advanced routing codes", then type:

VS / f bc=m

...for both outbound and return routing codes.

Pick your dates/flexibility, and that should be it...

NYLON

You will only need 40000 miles for a return reward in UC to NYC, we paid aprox £800 for a return M class.

Yes, £800 is a ballpark figure.

Thanks for all the info. Used the matrix but will only bring up o and n class fares on outward journey

Was quoted £868 for Boston M to a G earlier today start of Dec which I guess would be pretty similar to NYC