The good news is, a good few year old used unit can be purchased very inexpensively, and these machines are tanks, and are fairly reliable. So if you need drum scans, and have a lot of film to scan, owning a drum scanner can pay for itself very quickly. Labs seem to charge very high prices for drum scanning. Do the math and figure when your payback would be. For me, it was less than 2 years.
Drum scanners are large beasts.
Mine takes up about a 2 ft x 4 ft area, plus the drum mounting station has about a 4 sq ft footprint. So you'd better have room to do all this. You also need a very strong table or support system as the scanners weigh in at 150 lbs, some over 200 lbs. And they operate at high speeds, like 1600 RPM, so vibration can disturb anything in the vicinity of the scanner. Here is a look at the scanner I own, the Howtek Hi Resolve 8000 .