I found my copy of Dunn and Wakefield on Abebooks for about US$4, including shipping. It was printed in the UK, and so appears to be more common there. Abebooks.com typically has dealers with copies of the 4th edition (1981) for around $5-$6 including shipping, even shipping from the UK to the US.

Well worth the money.

FWIW, I worked in perhaps a dozen professional studios in the 80's, and never saw anyone point an incident meter dome anywhere but at the camera lens from the subject position (or equivalent). Dean Collins advocated pointing at the key light (in artificially lit portraits on low contrast negative portrait films VPS and VPL) and was the first and only pro I knew of advising this. I think his popular portrait training videos were widely viewed and his unorthodox and special-case incident metering advice propagated on the internet and elsewhere by people who didn't have wider training or experience as the correct method for all situations.

You can, of course, use any light meter in any way that works for you, but the design of the hemispheric receptor incident meter is made to replicate a three dimensional object as seen by the camera, which means pointing the meter at the camera from the subject position (or in the same direction, i.e. parallel to that line, in the same light).