How long do you plan on keeping it? Initial purchase price of aluminum is much less ($300-$600), but they sell for $50-$100 used. Fiberglass has a much higher initial purchase price (I was quoted $1200 for one that would match my Ranger) but they too sell for less, just not as much less (I paid $340 for the one I had, used prices seem to be between $150-$500). It seems to me you get what you pay for. I liked the weight of the fiberglass in the winter, but I hated that snow would get stuck between the cab and camper.
I wouldn't opt to purchase a camper again, I came to realize I could get the same utility from a wagon, wheras without it I can haul items taller than the cab of the vehicle.
Presently, I have an Extang Solidfold tonneau cover and I think it's great. It weighs about 50lbs, is made of aluminum so it won't puncture and it's secure. So far, no leaks and I've run it through the car wash. It folds 2/3s open if you don't need to haul anything big and you can take it off or put it back on pretty easily if you do need to haul something large (fits inside the bed lengthwise or it mightfit in the cab if you angle it in correctly). It was honestly a very good purchase, I like having it a lot more than a camper.