Try www.plumbingsupply.com and look under water softners. They have a good high capacity units and can ship to you. You can email them and they have a FAQ section on them. I've used Sears, who are made by someone else, and have had good luck but like everything else they have a life span and then wear out. Sometimes it is easier to use the card to buy than write a check. I sometimes wish I had a 1" high gpm unit cause the 3/4" will somewhat restrict the flow to a shower, etc.
Also go to www.plbg.com and search their forum for water softners. You will find differing views and that some units are overpriced. You do need to start with a water analysis to see what needs to be treated and not just a hardness test that some do. You may have iron, bacteria, and other things. Some companies like kinetico and others may be including filters and reverse osmosis units that may or may not be needed. You also need to size the softners. I prefer to go a little bigger so they cycle less. Also get ones that cycles by demand meter as opposed to the old style timered unit.