We live in Florida and have a small event facility. This facility is not open for business due to the economy. Eight months ago, there was an event held here and the people that held the event left several items. They returned to the facility several times over the following month and took several of the items they left. We had no problem with this. However, after that month there were still some items here and the customer never contacted us again. There was no formal or written agreement for the event or storage of anything they left.

We eventually sold a bunch of our stuff and the left items (about a month ago) to pay bills. Then today we got a phone message that they want to come pick up the items and claimed that some of the items weren't theirs but were borrowed. The total we got for selling the stuff was about $200.

What is our responsibility to these people?

Did you send them a final notice stating that they had a deadline to pick up the stuff? If no, you may have a responsibility to reimburse them. Without something in writing indicating they could not leave the property past a certain date, they had no expectation the items would have been removed or sold. Even though it may have been unreasonable for them to leave the items for so long, I think a court will rule that you needed to give them a deadline.

I am sure you sent them a letter, perhaps a copy certified, giving them a specific date to have it out out by.

Florida has no statute of limitations on abandoned property. Owners can claim property at anytime. When you sold their property without notice and/or permission you likely violated state statutes. To sell something you are claiming to be the legal owner, you were not. As you said , the property is closed so there was no immediate need to get their property off your land so the courts, if you end up there, may take a dim view of your actions