Oh boy. What a can of worms you have opened up Starman!
I have heard a number of stories about adverse reaction to rabies vaccine. I have never met anyone who had a problem, although I am sure there are people out there.
As labman pointed out, in the US it is the law for dogs.
Starman, that first website link you gave is not one I would recommend people read. It is about a person receiving the shot who developed problems, and the response received is not based on fact. The second site looks like an article that is based a little more on reality. Yes, vaccines are marked up tremendously. I cannot vouch for the price paid by each vet but I do know that when we have the rabies clinics in my area in the springtime, you do pay much less than you would for a private visit. Those clinics are mainly for people who have financial problems, but who are responsible pet owners concerned for their animal's well being. Every year the local vets rotate who will run it. Their primary concern is to get animals vaccinated. It is the law for a reason. We have too many wild animals who contract rabies and we need to protect our pets.
Did any of you read the articles last year about what China did? They did not enforce laws requiring vaccinations and there was a major rabies outbreak. Dogs bit people and it was becoming a rampant problem. So, the government ordered the police to kill all the dogs they found. Police forced their way into people's homes and clubbed their pets to death in front of them. Extremely harsh to say the least. That is a sad example of why we need to follow the laws here. Whether we like it or not, whether pets can become ill, whether the cost may be a bit high, this is a regulated vaccination that needs to be administered. Just keep in mind that vets have quite a bit of paperwork to fill out and submit to the government. The cost of paying people to keep the records straight is factored into the price.
In any event, the website labman provided is one that is regularly used for reliable information.
Here is another one written by a vet. Scroll down the site to get the side effects info.
Frequently Asked Pet Health Care Questions