It's an expensive trial and error thing to do when it comes to painting the exterior of your house. You usually do get what you pay for.
Before you decide about who is right check out Rhino Shield. It's a system of coatings that does what we all wish paint would do and changing colors with one application is no problem. You can Google Rhino Shield and all of the dealers will be there. Check out one of the sites. They do a turn key job including over the top prep., wood repairs and the application of the coating system that carries a 25 year warranty. It's also independantly tested by BASF. I have it on my house (3 1/2 years so far) and it still looks brand new!