Grabovski, who is the least expensive option, was placed on unconditional waivers yesterday and will be bought out after noon ET by the Toronto Maple Leafs, making him an unrestricted free agent.
With roughly $13 million in salary cap space, the Blues need to tread lightly. They also have to re-sign restricted free agent defenseman Alex Pietrangelo, right wing Chris Stewart and goalie Jake Allen.
Signing those three players alone will likely put them up against or over the cap. The addition of a center or top-six forward will undoubtedly force them to make a move.
Another player the Blues have been linked to is veteran right wing Jarome Iginla, who isn't expected to re-sign with the Pittsburgh Penguins.
The Blues have been shopping goaltender Jaroslav Halak and left wing David Perron in an attempt to shed some salary.
Armstrong had also been shopping Stewart during the season and could opt to deal him if contract negotiations become too far apart.