Here our local school district is required to test, if you ask them. Of course it's free, but you are essentially on their schedule, which now that school's out may not be until Sep/Oct. If money is an object that may be a good starting place. Of course sometimes you get what you pay for, so be aware not all districts are created equal.
He sounds similar to my ds.... late talker, not getting certain multi-step directions. I remember asking the ped what he thought back when he was really young. He asked if there was any "dimness" in our family. My dh was insulted, but, frankly, not everyone is born smart. Not saying your ds isn't, just made me think at the time- I had never thought of the opposite of brightness. My ds is above average IQ and is now an excellent reader, but really struggles with writing and any noisy distractions, among other things.