Is There An Effective Way To Easily Compare Printing Services In Terms Of Cost And Quality?

There are seemingly thousands of different printing services out there, but it seems very difficult to compare among them. I find myself visiting many different companies and spending a great deal of time trying to compare them.
There are price comparison search engines for products, but I don’t know of any for printing services. Do they exist? Even just a general printing service price tracker?
There is also the question of quality – do any sites review and compare the quality of services?
Even if there are no quality review sites, simply a good price comparison tool would be helpful. Most printers can make arrangements to provide samples, allowing the quality question to be answered.