After taking a look at the Camplites, they're really not much different from anything else you'll find out there and the majority of any parts you'd need would all come from the same places.
That being said, I'm not sure I'd recommend a behemoth like this as anyone's "first pup" as the bigger you go, the more opportunity you have for costly repairs. Additionally, you can't just contact the manufacturer if you have problems. If you're mechanically inclined, if it's a great price, if EVERYTHING works, if it's in PRISTINE condition, and you're not too concerned about taking the plunge, it's your call.
I doubt there are many, if any parts stamped "made by Damon". The lift system is most likely a Goshen, so I seriously doubt you'd have any trouble finding parts for it.
Axles, springs, brakes, tires and bearings, plumbing, A/C, heating, lighting and electrical components, exterior plastics, access hatches, that sort of thing are all standard across the industry and can be found at any RV dealer.
Since most canvas shops that specialize in popups would use your canvas as a template anyway, replacing the fabrics/canvas is a non-issue.
This Camplite roof rebuild thread might come in handy:http://www.popupportal.com/index.php?topic=15636.msg51992#msg51992
My advice? As with any used pup, check the floor inside and from underneath for soft spots and rot, particularly under the lift system brackets and inside the door. Look for water stains on the walls as well, particularly around lift posts. Check the condition of all lift cables, winch and pulleys. Electric lift? Make sure it works properly.
Visually inspect the roof behind the canvas, particularly in the front and rear at the tops of the bunk canvas for rot. Make sure the bunks slide in and out EASILY. Make sure the walls are all solid and that the door is square. Check the floors in the storage compartment for soft spots and rot as well.
Make sure the fridge, stove and plumbing are in good working order. Check that the converter is working and check the dates on the battery (batteries) to ensure they don't need to be replaced (The average service life is five years for batteries).
Check the date stamp on the LP propane tank (They have to be replaced every ten years). Try the furnace and A/C as well. Crawl underneath to check for frame damage in the front and rear. I'd want to see that frame straight as an arrow, no appreciable sagging or flexing.
Remember, you MIGHT be buying someone else's problems. It happens, just don't overpay for them!