Tolvanen signed for 1.5 the other day. These types of players are always available, you should not pay a premium for 4th liners in pretty much any scenario unless you (and other teams) are pretty certain they are going to break out and you play them in an elevated role
I looked at EV xGA vs XGF rapm and highlighted which forwards are still not signed. A lot of these are players with low production + minimal impact on both sides on the puck, mostly negative on the offensive side, which I'd argue is alright for a 4th liner. Given the uncertainty