Alex Snitker, the Florida Libertarian Party nominee for U.S. Senate, has qualified for the ballot by paying the very large filing fee (slightly more than $10,000, although a relatively small part of that money goes to the party). See this story.
He is the first Libertarian Party candidate for U.S. Senator to be on the Florida ballot. The only other minor parties that have had a candidate on the ballot for U.S. Senate in Florida since 1924 are the American Party in 1974, the Natural Law and Reform Parties in 2000, and the Veterans Party in 2004.
The only other states that have never had a Libertarian on the ballot for U.S. Senate are Arkansas, Maine, Maryland, and Rhode Island. The Maryland Libertarian Party is ballot-qualified and may nominate someone for U.S. Senate. The Arkansas Libertarian Party is attempting to become ballot-qualified and if it succeeds, it may run someone for U.S. Senate.