@FlyingLow Generally people will tell you to stock up in Maine versus Massachusetts. Maine has less requirements so smaller growers can put out higher quality at lower prices (in general!) I highly recommend checking out the reddit communities BeantownTrees and mainetrees. You'll find tons of recommendations and reviews. (Avoid bostontrees, it's just a marketing front.)
Definitely worth springing for a med card if you can, as you'll get access to the best quality in Maine (and they take out of state cards.) But not a 100% necessity. Rosin in Maine is top tier. I don't do concentrates so can't speak to specific growers. As to flower, Braveboat, Bungludetch Farms, Woodstock Farmacy, Firefly Organics and Mentation are all amazing. Also had good luck with Tastefully Baked.
For MA, there is a lot more crap on the market. Good brands right now are Bountiful Farms, Native Sun, Harbor House Collective (if you go to their location in Chelsea), and Tower Three. People tend to agree that Bountiful has the best rosin in the state. They are also doing some interesting flower strains lately. Worth a trip out there for sure!