The most important part to check is the lens. Cock it and fire it, listen to it at various speeds, The time should be noticeably different at the slower speeds. The slow speeds will go bad first. Open the lens and stop it down- the blades should all close down evenly. Make sure you can focus across the entire frame. Focus on a newspaper- it's a quick way to see lens aberrations.
   Then check the bellows. Remove the lens and hold the bellows near a strong bright light. Throw a dark cloth over your head so the only thing you can see is the inside of the bellows. Any pinholes will ruin your shots. ANY pinholes. You can tape them as a stopgap, but the tape will work loose on your most important shot.
   Check that the movements are smooth and even, no corrosion on rails, and that you can lock up the various movements. Make sure the springs on the film holder are strong. It should be a very tight fit to open the film holder. Otherwise, you will get light leaks as you remove the slide.
   This is a 4x5 camera. Unless you are familiar with 4x5 film, you need to learn how to load and unload this film ,as well as how and where to get ti processed. If this is the wartime Graflex, i don't think the roll film back will fit, but I'm not sure.
Keep in mind there were many models of this camera. That prices seems high. I would only pay that for something in museum or collectible quality condition.

- How would you go about assessing a cameras quality without being able to shoot a test roll?

You have so many things to learn

 The most important part to check is the lens. Cock it and fire it, listen to it at various speeds, The time should be noticeably different at the slower speeds. The slow speeds will go bad first. Open the lens and stop it down- the blades should all close down evenly. Make sure you can focus across the entire frame. Focus on a newspaper- it's a quick way to see lens aberrations.
   Then check the bellows. Remove the lens and hold the bellows near a strong bright light. Throw a dark cloth over your head so the only thing you can see is the inside of the bellows. Any pinholes will ruin your shots. ANY pinholes. You can tape them as a stopgap, but the tape will work loose on your most important shot.
   Check that the movements are smooth and even, no corrosion on rails, and that you can lock up the various movements. Make sure the springs on the film holder are strong. It should be a very tight fit to open the film holder. Otherwise, you will get light leaks as you remove the slide.
   This is a 4x5 camera. Unless you are familiar with 4x5 film, you need to learn how to load and unload this film ,as well as how and where to get ti processed. If this is the wartime Graflex, i don't think the roll film back will fit, but I'm not sure.
Keep in mind there were many models of this camera. That prices seems high. I would only pay that for something in museum or collectible quality condition.

Thanks a lot for that info, really appreciated! I'll definitely keep those in mind when I go over!

You have so many things to learn

Don't we all, don't we all... And now I already know a bit more than that antique dealer guy

Shine a bright light through the lens to check for the presence of any fungus.

 Now there's one i didn't know! I'll have to go look at my view camera lenses and see if any fungus is growing, since I haven't used them in so many years.

I used to work at a company that sells used equipment, my job was to test the cameras, lens, etc...  The ebay id is shutterblade and they sometimes get those in although finding one that works well is rare, probably because a lot of them were well used 50 years ago and then spent the last 20+ years sitting around in a closet.  The lens is usually the part that goes bad, fungus, shutter speed, lots of dust etc..  Good luck, we did get very nice ones every once in a while though so you may find one.  Also look at KEH and usedcameras.com these are all reputable companies and on ebay you still might get a good deal and can see the pictures in advance.

This is the camera that Weegee used in his documentative photography in NY during the war-years, it was one of the fastest of its time. lovely!!