I personally don't see any problem with someone posting up if they have seen a good deal especially if it saves someone money when buying gear which is a big outlay for most people.
For similar reasons I don't have problems with shops promoting good deals. Obviously if misleading information is put up then this should be pointed out but I think most posts including this one have been put up in good faith.
I've benefited from these posts and have bought from local businesses which i would prefer. In the past I sometimes bought from abroad because there weren't great deals locally thus sending money out of the country. Therefore the more information posted on local businesses the better!