bought the Hogue rubber monogrips to 'test' the fit on my 4" .32M SP101 before ordering the same grip in pao ferro. Sadly, even though I love wood, the rubber grips are fine - and I can't see me letting go of that much moola anytime soon.
I will concur. The cocobolo grip in my picture above is from the seconds auction site. I am pretty sure I got it for under $30.
You can find wood inserts for your factory grips that look nice.
FYI, Lett's is out of business. Kaputt.