How about feeding them?
Burms take up a good amount of money for feeding with rabbits costing an average of $1.50-$2.00 a pound. A large 100lb burm will need a 10lb rabbit atleast once every other week. So you're looking at $15-$20 for one feeding, and if fed once every other week that's $30-$40+/- per month. And year-round you're looking at $360-$480 a year.
And monitors are just hell. They feed just about everyday. When it gets bigger it's going to require meals from colossal rats, guinea pigs, chicks, maybe small pigs, and small rabbits. That's money I wont even begin to calculate. A friend made a mistake of buying a young water monitor. Was feeding on a dozen goldfish and 2-3 rat pinks a day. He then found it was taking too much money (coming from a guy who makes $100,000+ a year) so he offered it to me. Which I wasn't about to do because I know there is no way in hell I could take care of one with a small paying job and breeding rats.