40K seems very low for a D2 team. I make 40K with my 3 home drafted guys and a number of other Americans. I've heard of all/mostlyl American teams in D2 making 75-90K in merch.
Also, the promotion bonus affects merchandise too. When I promoted to D3, I was making 45-49K in merch (even with lowish salary home draftees). Seeing as you've promoted every season, you're getting decent merch even with mostly transient, foreign players. Once the promotion bonus wears off, you'll likely be making a fair amount less.
Now, merch is not likely to ever be a make or break thing. But at some point, most teams earn about the same revenue, so the extra 10-20K means a good depth player, or some scouting, or just extra 140K over a season.