Moyes celebrated 500 games as the Toffees boss with a 2-1 FA Cup fourth-round win at Bolton on Saturday and is under no illusions regarding the budget at Goodison Park.
"When I took the job 500 games ago, I knew the situation wasn't going to be having lots and lots of cash to spend," said Moyes, quoted in The Sun.
"I cannot suddenly turn around and say 'Hey, where's the cash?' because that wasn't in the agreement.
"I was reading in the programme before the game that in the past 10 years we have only finished in the bottom half of the Premier League twice so we have improved as a club and grown.
"A lot of my time in the next week will be devoted to trying to get someone in but more of my time will be devoted to trying to win the games we have.
"I will tell the chairman what we need and hope we can do it together. I know exactly, he gives me every penny.
"We are pretty straightforward at the club, if you don't have it you can't spend it. But if I have to have a bet on whether we will get someone in, then I would back myself to do it.
"I can't tell you which position we are looking for because sometimes in the January window it's a question of looking for a number of options and seeing who comes along."