I think they are supposed to be the same price no matter where you go... at least that was what i was told back when i lived in Mo and had to deal with that.
they should be the same no matter where in the state you are.. like in TN its 10 dollars for emmissions testing, no safety testing... pre-96 is just a sniffer up the tailpipe, post-96 is code reading and sniffer..
and you do this every year, unless you have a non-emmissions vehicle, or a "antique" tag and registration, has to be older than 25 years and theres a long list of restrictions of where/when you can drive the vehicle...
Safety inspections are mandatory in my province. Basically, it confirms that the vehicle is safe for use on public roadways, and MUST be done before any vehicle is registered.
Price from shop to shop is pretty uniform.. If one shop was much cheaper, everybody would go there. We charge $45 + taxes where I work.