No, I didn't even think of one of those! Do you know how much a normal one would be, like the average price?
You can get one for maybe $15-$20 for a tank that size at Petsmart or Petco. Since you haven't been vacuuming each week I would only do half the tank one week & then the other half the next week. Push the nozzle down into the gravel to get the debris that may have settled into it. Remember the gravel vac also removes water so watch how full your bucket is while you're doing it. I've almost overflowed a bucket or two. Vacuuming well should also help with the cloudiness.