Yeah, they are quite hard to find. I have one in my collection. The base seems to be easier to chip than the more common standard base. Could be just my example though.
Thanks for the responses everyone. It seems there are a few more out there than I thought. Judging by the responses I'd say they are still fairly rare compared to the smooth base and we all know how seldom even those are seen. I would say in my 10 years of collecting I've only seen a handful of smooth bases for sale and no grooved base examples (besides the one I bought from a non-collector).
Does anyone know first hand what line or area the grooved base examples came from? The one in my collection came from a person in the Port Perry area who had bought it in a lot at a local auction.
This one just sold on Ebay. It's the only one I can remember seeing on Ebay in 10 years. The grooved base is different from any other grooved base 143.
Interesting. I think I have seen some Can-Pac CD 143's with a base like that but not a GNW. I will have to keep an eye out for one. Thanks for posting the pic.