We are looking for a peaceful country that has good English speaking schools for our kids that are affordable. Most International Schools that we have looked into are expensive.
Does Costa Rica have any good English speaking schools grades 5 thru high school ?

There are several schools that have three out of five classes taught in English as well as a predominantly English-speaking community, in a group of schools called CATIE. There's one in Turrialba, in the Central Valley region, right in the mountains. However, I find it odd that you would want to move to a different country with a different language and not have your children learn said language. Most people speak Spanish there and I think it would be wise to have your kids attempt to do the same. If they attend an English speaking school, then they will not experience life as Costa Ricans do, but as many English-speakers do. That defeats the purpose of moving to the country in the first place. I highly recommend living in Costa Rica, as I did for a long while, but I would advise that you steer away from English and embrace the Spanish of the nation.