There's no such thing as a standard agreement, but I have good news for you.
I once worked alongside a certain flight organisation regarding a similar agreement. It's a bit risky not getting legal advice at all, but you can cut down a lot of the unnecessary legal fees by drafting the initial version of your own agreement in your own words, like telling a story. Make sure you conclude all your negotiations with your fellow shareholders internally first. Then include in your draft everything you want to see happen, the things you don't want to see happen, and how things should be dealt with if things go pear-shaped. That way your lawyers would not be able to take you for a ride and use that excuse to overcharge you. Tell them you do not want an agreement more than one page longer than your version. Also, make your lawyers agree to a fixed fee before you start. They'll hate you for this but if they want your business, they'll have to play ball.