This is my first year to manage a USTA league team. Money invested is very little. Just USTA membership (I did 5 year) and team fee ($15 or $25 I think... I can't remember). Other fees are just supplying the balls when you are home team. As far as managing a team, you need a surplus of players. With everyone's busy schedules, it is sometimes hard to get 8 guys together. 2 singles and 3 doubles. I think we had 19 on our team, and there were some matches I barely got 8 together and some where more than 8 really wanted to play.
Being team captain you really have to know how to manage egos and keep everything as fair and happy as possible. If you are just doing it for fun, then you can rotate the guys pretty easily. If you are doing it for the competition, it gets pretty sticky. You always want to put the best available. You can't just forget the less talented, because you may really need them, especially when they are the only ones available. Tennis is such an individualistic sport, and many people have a hard time putting a team mentality like football or basketball. There always will be players who think they should be the one to play.
After a 15 year layoff from tennis, I started playing again last year. Some guys saw me playing and recruited me for their 4.0 team. I was pretty rusty and couldn't keep up. I went winless, but it was fun. (They also happened to be the last place 4.0 team.) Luckily I self rated as a 3.5. I got in better shape, joined a 3.5 team, and started winning. I think I can play at the 4.0 level now, but the new country club I am in is so competitive, I can't make the 4.0 team. They are a bunch of 4.5 players if you ask me, and yes there is a lot of sandbagging at the competitive level.