The Blades looks certain to make new signings following four moves out of the club prior to the transfer window closing last Monday at midnight with; Chris Armstrong (Reading), Jonathan Stead (Ipswich Town, loan), Michael Tonge (Stoke City) and Ben Starostra (loan) all leaving the club for pastures new.
"We've already got something lined up, I'm hoping something will happen before the Derby game on 13 September," Blackwell told BBC Radio Sheffield.
When you are up near the top of the table your player valuation rises and that enables us to get a good figure, and that allows me to look at different options," he said.
"I've got two people in mind, we've spoken to the clubs and there is a strong indication that we'll be able to do that in 10 days' time," he added.
Blades-Mad are under the impression that either one or both out of Michael Brown (Wigan Athletic) and Brian Howard (Barnsley) will become a Sheffield United player sometime next week before the Blades travel to Pride Park.