Many NHS hospitals in England are paying over the odds for supplies, a snapshot investigation suggests.
The assessment by consultants Ernst & Young highlights big variations in the prices paid for a range of medical products.
The findings come despite long-standing concerns from MPs and the National Audit Office over wasteful procurement.
The Department of Health says it is developing a barcoding system to help hospitals negotiate better prices.
The NHS is coming under enormous pressure to find savings. But nearly two years after the National Audit Office (NAO) highlighted waste in procurement, this assessment suggests some hospitals are still getting poor deals on supplies.
In February last year the NAO concluded better procurement could save the health service half a billion pounds a year.
For this investigation, Ernst and Young looked at 10 NHS hospital trusts out of 166 - and found the prices paid for the same box of medical forceps ranged from £13 to £23.
For an identical box of blankets the lowest price was £47, the highest more than £120.
The assessment revealed big variations across a range of other medical supplies including knee implants, syringe pumps and warming blankets.
Joe Stringer, from Ernst & Young, said the discrepancies were "staggering", and he warned that the problem was getting worse. Trusts, he said, were reluctant to share information for fear of helping their competitors.
"With the NHS facing sustained pressure to contain rising costs and demand within a flat budget, transparency must be introduced across the board.
"The consequences of inaction in the back office will only be felt more acutely in front-line care."
Earlier this year the government said better purchasing could save the health service in England at least £1.2bn over the next four years, and announced plans for a "world class" procurement system. This included a cash fund to allow bulk-buying of equipment such as MRI scanners and ultrasound machines.
Responding to the new findings, the health minister Lord Howe said wasteful procurement was unacceptable.
"We are working on introducing a new barcoding system that will increase transparency, save money and make care safer.
"The new system will take time, but ultimately it will result in the kind of price comparison website that already exists in other sectors, like supermarkets, and will revolutionise the tracking, safety and use of clinical products bought by the NHS."
The chief executive of the Foundation Trust Network, Chris Hopson, said trusts understood the importance of good procurement.
"NHS Trusts know that they need to improve how they buy supplies to get best value and they are making good progress through a variety of different routes including commercial purchasing consortia and regional NHS procurement hubs.
"Price comparison websites and better public information on how Trusts are performing in this area will undoubtedly help drive further improvement."
Shadow health secretary Andy Burnham said: "The government is encouraging hospitals to think and act like independent businesses. As a result, they're losing the potential for the NHS to use its collective buying power. Market-based health systems cost more not less and this is one of the reasons why."
Julian Trent, from the NHS price-comparison website Peto, said price visibility would reduce costs.
"The government's current review of procurement practices must put an end to unethical charging within the NHS so that trusts can purchase supplies of best value and quality."