Here is my .02 worth

I would take a good look at the engine compartment, v-drive (under the center rear seat), and ballast pumps (under the panel to the left of the drivers seat). On a boat with 75 hours, these areas should be pristine. If they appear dirty or grimey, then I would worry about the actual hours on the boat (or where its been run). If they look as good as every other picture (which I suspect they will), I would assume the hours are true. Next, I would definitely take the boat for a spin. Make sure you check full speed (which should be around 5.5K RPM to 6K RPM (depending on the prop etc...) and should get you around 38 MPH. Check to ensure the steering can go full left and right (with no binding) and also check that the ballast fills and drains properly (this will take at least 10 minutes each). One problem with some SX's (including mine) is the internal ballast. It will fill properly and indicate full, but after riding for about 5 to 10 minutes, one side will slowly drain in to the bilge. I have heard of this from 2 or 3 different folks and think it is a flaw in the internal tanks (note: the 2001 and 2002 ballast tanks are a bit different and yours may not be identical to mine). Either way, I would fill it and then run it for about 5 to 10 minutes at wakeboarding speeds and double check the indicators. From the pics, it looks as though it still has the accuski pedal and system, so make sure they show you how to work the system (it is not terribly easy...and definitely not as convenient as Perfect Pass). Last, I would check the trailer to make sure the tires , bearings, and winch are all in good shape. Since the boat doesn't have many hours, the trailer may not have been serviced too often. Check to ensure the tires have not begun to crack (even if they look barely used) and make sure the bearings are greased. The last area to check is the wheel wells. Make sure there is no damage on the insides (from a blowout). Overall, that boat looks to be in great shape and I would imagine most of this will be fine. I can't imagine the seller turning down 30k, so I hope you enjoy your new boat.
Ktown