From my experience, it all depends mainly on the kind of work you want to do. If you are doing TV, Movie, National Jingles, Master Record dates, Theater Pit Gigs , or Symphony work membership is a must. The AFM keeps up with your payroll, reuse checks, benefits, and pension. They negotiate the pay scale and benefits for the Symphony Orchestras and other types of venues.
And, if an account stiffs you or gives you a bad check, they'll collect for you.
They do set a minimum scale for the different types of work, but you can negotiate above that, depending on your relationship with the account or contractor. I usually work for double scale and sometimes more. What you actually make for has to do with your talent, reputation, experience and negotiation skills. Scale is a good place to start. Since, most of us don't appreciate what we are really worth.
You can make some great career contacts by being in the Union that you would never make elsewhere.
If you are on the road with a band and traveling, being in the Union (using signed and filed Union contracts for your gigs) offers you some protection in the case you get stiffed by a promoter or the venue.
When I was on the road years ago, we got stiffed by a club in Kansas and were pretty muck broke. The Union got us some cash to help us get back on our feet and they collected our dough and got it to us. We would have been totally screwed were it not for the AFM. They also collected the money for me from an album that I was the session leader and played on too. The record company was trying to pull a fast one on us and the AFM stopped them.
Some states are right to work states, which means you don't have to be in the Union to work and you can work along side of Union players (if you get hired, which isn't likely) but you aren't protected if you get screwed or do you get any benefits. Some states, Union membership is pretty much a requirement.
There are 2 dues.
1. Your monthly local and national dues..they are a combined amount. National dues is the same everywhere, the local dues varies by location.
2. Work dues, a percentage that is paid to the union on each gig contract that is filed. It is usually factored into the total amount of the contract and doesn't come out of your pocket per se.
No one can tell you to join or not, it depends on your situation.
I don't know a Union player that has not done a scab or non-union gig. Getting caught used to be a big deal with fines attached if you got caught. It all depends on how strict the local office is regarding it.
But remember, if you do work non Union you are undermining yourself and the organization.
Just my 2 cents.