Some managers (and to be fair, some contracts for environmental work) obsess about budgeting out exactly what's needed for a field job. How many rolls of paper towels? How many boxes of gloves? What's the cost of each size of cooler? Can we order only 68 sample jars?
It's the field. Stuff happens. You drop your roll of paper towels in the mud, or it rains and everything gets soggy. You get some new field folks rotated in who have ham hands and you run out of the extra large gloves. Sample jars break; if you're lucky, they break before you finish up at the location and not on the last day of the job, when you're packing up the last shipment. You break the last screwdriver trying to open a well cover.
When I budget for fieldwork, I tend to order what I need for each phase of work as if it exists in a vacuum. That way, I can scrounge from the previous job's leftovers if I go through more supplies than I'd anticipated.
I also don't sweat the small stuff. Having a complex formula to minimize how much strapping tape should be used to seal a sample cooler is foolish when the stuff in the cooler is worth several thousand dollars' worth of labor. Please, take all the tape you want! It costs $5 a roll! Wrap the cooler in a web of tape that will take 20 minutes to open, if that's what you want to make sure that it arrives at the lab intact.
Instead of breaking out every single plastic bag and glove, I usually go the other way when budgeting. Take a nice, round number that has some thought behind it, and put in "consumable sampling supplies - $40/day" or whatever, and be done with it. Nobody really wants to go through a long price list of basic sampling supplies.