Prior to this year, I would do close to 100 games a year, and it was for a number of different stations. I was lucky enough to usually borrow someone's equipment, but there were certainly times that I could have used my own. It was never enough to make a full time living, but at the time I was a radio news reporter at ARN so as you can imagine, the extra few hundred a month might make a difference in getting some bills paid. There are a lot of radio operators who find themselves needing play-by-play people at times...
It sounds like you have enough to put together some equipment.. JK Audio makes a "PhoneTap" that would interface from what you have to a telephone. I think that runs about $80.00 or so... You could probably make it work.... If you were to run across about $500 or so, you could probably find a JK Audio Remote Mix... they show up on EBay every once in a while, and I might be overshooting the price. I haven't quoted one in a while. That might not be enough...
As far as your own enterprise goes, you might be able to pull together something like this.. an internet only radio station certainly is ahead of it's time as me and Lyncho found out at one time, but one thing we were able to sell was high school sports. There are schools out there especially in metro areas who aren't getting coverage from local radio, and are BEGGING for ways that alumni can connect. It might not be enough to sustain a full time living, but one might be able to make a dollar or two by broadcasting some of these schools where there is a strong financial backing behind the teams. Same thing for small colleges.... in my case you wouldn't believe the people who listen to Ouachita's webstream during basketball games... it's not necessarily the numbers that are impressive... it's the people who drop an e-mail and tell you they appreciate the call of the game.
You can always find people to do play-by-play for (even if you are pretty mediocre like me!!)... I'll look on the internet later tonight and get more details on the equipment I listed above and report back...