Depending upon what you want out of this you can bring what's called a "replevin proceeding" (return of property) or "tortious conversion" (monetary compensation for the fair market value of the property lost). Even though the property is yours, because they fired you and your property was in their possession, the band has an obligation to keep it reasonable safe and secure. They also have an obligation to provide you with access to it.
Depending upon the circumstances of the firing, they may even be responsible for covering the shipping to return it to you. If they fired you from a distance it may be constrrued that they also accepted the responsibility to return your property to you at their cost. Though this will depend upon what your state court's allow. A lawyer in your state should know the answer to this one.
In either instances above (Replevin or Conversion) you can recover reasonable costs and dispursements in bringing the claim to court. You might (though this isn't a slam dunk) recover attorney's fees. However, there needs to be some bad behavior on their part in order to get that back.
Save your correspondences and emails that you might have received from these guys. Also start compiling documents to support your ownership of the equipment just in case they try to deny that you ever left it with them. Photos, purchase receipts, serial numbers, or maybe you listed them in your property insurance forms with your insurance company. These are all valid forms.
Then see an attorney and have him or her send a demand letter for the immediate return of your property "or else....". You'll need to start a paper trail of at least one letter showing a documented attempt to get these items returned. That will help your case and may bring you closer to getting your attorney's fees paid for by this band.
Hopefully it won't come to this. Usually a demand letter on a law firms letterhead will get their attention. No one likes to deal with lawyers in disputes. It's too much of a pain for them. But hiring a lawyer to write a letter and deliver it certified will be a decent and inexpensive deal for you.
There you are. That's my legal advice...And I won't send you a bill for this one either.....
Jazz