Yea, Gavin, get on the ball
Rangefinder comes with WPPI membership, and like Mark wrote, they'll give it to you free if you ask. I got mine free for a year before I signed on with WPPI.
And I disagree that you get nothing with WPPI. For one, you get professional membership recognition which can be valuable in the minds of your clients ... they consider your affiliation as being active in the pro community.
Plus, WPPI does offer a number of other services to members, not to speak of the prestigious print competitions and Trade Show.