Bolton boss Neil Lennon is unsure how many more signings he can make because of the club's financial situation.
In April, the club announced their debt had risen to £172.9m after a loss of £9.1m for the 2014 financial year.
Ben Amos, Gary Madine and Derik Osede have joined Wanderers this summer, along with youngsters Jon Ceberio and Jordan Lussey.
"It's a big challenge because we don't really know where we are in terms of what we have budget-wise," Lennon said.
The 44-year-old told BBC Radio Manchester: "We are looking at trying to get value for money, it's difficult.
"But we're hoping that we're going to be down the line with one or two deals in the next week or so, that will enhance the squad.
"A number two goalkeeper is a priority and a right-back obviously, another centre-forward and there may be one or two going the other way as well."
Bolton have forward Stephen Dobbie and right-back Lawrie Wilson on trial and both played in Tuesday's pre-season win over Oldham, while BBC Radio Manchester understands 37-year-old former England striker Emile Heskey is close to signing a new deal.