And know the vendors. What is their track record? Many physicians have been burned selecting an EHR because they invested in systems that were sold to them by vendors who are no longer in business, and they end up with no tech support.
The system I bought cost more than I initially wanted to spend. I wanted to do it for pennies, but I finally realized that if was going to do this, it was worth it to spend more money and get more of the things that I wanted. Dollars can be shaved off software licencing and tech support fees by being realistic about the number of workstations you need at any one time for scheduling access vs patient chart access.
After you have a system in place, have a backup plan for when the system breaks down. My system never went down for more than a few hours. I never lost data, but I have heard horror stories from colleagues that did. So good luck. This leap of faith will pay off in unexpected ways. Just be sure to back up your data religiously.