I am one who can view this situation from both angles. I was once a young, aspiring, upcoming, drummer in the DC area and when I would witness and hear about the kinds of things mentioned in this thread, I decided that I would hone my craft and just play at my home church where I didn't get paid anyway and it was never an issue.
I didn't want to put in the rehearsal time, gig time, gas and driving time only to be stiffed at the end. I just didn't want to go through all that. Now fast forward 20 years, I am the Treasurer/Bookkeeper for my church. At our church musicians are treated as independent contractors (1099) or employees (W-2). We run payroll on a monthly basis and musicians are told this upfront so there is no expectation to be paid following an event or service. We have a flat rate for drummers, keyboard/organ/piano, guitar, and bass based on the rehearsal time, and event/service time.
It doesn't matter how good you are or think you are. The rate is what it is - there's no negotiating. The Worship Department has an annual budget for spending from choir robes, hymnals, to musicians, etc. It is the responsibility of the leader of this department to budget his/her programs accordingly. However, in light of this statement, the budget means nothing if the funds/offerings don't come in or our lower than projected. The sponsor of a particular program has to get their budget approved through the Worship Department before the event/service can take place. If they are bringing in guest musicians, I require their W-9, W-4, etc. before checks can be cut.
We don't mail checks because mail does get lost and can create a problem with having to void and re-issue checks. My point in saying all this is that churches, ministries, Bishops and so forth are dishonoring God with this type of behavior. It is downright wrong and they will be held accountable by God. As some have said, in this economy giving is down in most churches. If that is the case for a particular church, then they have some tough decisions to make. Do I pay the church's utility bills and operating expenses or do I bring in an all-star band/group to sing 2 songs and roll out.
In most cases, their going to pay their bills, and stiff the musicians if they have not planned carefully. Churches who treat musicians or anyone who has been promised pay are bad managers/stewards of God's money. Just this weekend, I was setting in the church office trying to figure out how we're going to pay the pastor, pay the musicians, and pay the bills. It's a very tough position to be in, but the responsibility lies with the church.
God bless you and keep doing what you're doing. God will honor your sacrifice and your reward will be greater than a bounced check or an unfulfilled promise.