Speaking to IT Pro, he said the sites in question are usually unregulated and it is impossible to tell where they have sourced their low-priced licenses from.
"These sites have no regard for Microsoft's licensing rules and we also know they don't buy from authorised distributors," he said. "The problem is, as soon as Microsoft closes one down, another opens."
The chances are the lower priced license is not worth the paper it's written on.
"Common sense is the only check. If the price everyone else is selling a license to you for is a good deal higher, the chances are the lower priced person's license isn't worth the paper it is written on."
Concerned firms should try and renew their licenses before 1 July, added Trish.
"If they renew or start a new contract now, they will have the prices fixed for the period of their contract," he explained. "So, if they decide to pay annually on a three year contract, they won't have to stomach a price rise for another three years."
Meanwhile, Clive Longbottom, service director at market watcher Quocirca, said the price changes could backfire on Microsoft, as few firms are in a financial position to cope with extra costs.
"SMBs may take the view that buying software without support or upgrade rights makes more financial sense. Then, when Microsoft brings out new software, there is less impetus to upgrade," Longbottom told IT Pro.
"If a support subscription to an open source Office system, for example, comes in well below the cost of a Microsoft agreement, firms may decide that free open source software is a better option."
Microsoft was unavailable for comment at the time this article was published.
