You have a good memory and that is correct. There are several states that I'm aware of that do in fact allow charging the owners for long term storage in Domestic Violence Cases. For example, here in California the Family Code - 

6389(e) A local law enforcement agency may charge the respondent a fee for the storage of any firearm pursuant to this section. This fee shall not exceed the actual cost incurred by the local law enforcement agency for the storage of the firearm. For purposes of this subdivision, "actual cost" means expenses directly related to taking possession of a firearm, storing the firearm, and surrendering possession of the firearm to a licensed dealer as defined in Section 26700 of the Penal Code or to the respondent.

Those departments that are taking advantages of statues such as here in California are usually charging a specific dollar amount such as $75 to submit the gun and an additional $5 per month.  In most cases the fees much be paid before the release of the gun.

 

Another example would be Massachusetts, where some gun stores provide storage vaults for a fee. When the owner is mandated by the courts to turn over a firearm, they are allowed to have them stored at that facility. 

As a side note to the issue of guns clogging up our property rooms, the US Supreme Court recently ruled in Henderson v. United States (May 18, 2015) that the sale to a third party is legal. Included below is a copy of a blog post from the United States Supreme Court posted on May 15th, 2015

After oral argument, the outcome in Henderson v. United Stateswasn't really in doubt. The entire Court had expressed skepticism of the idea that a firearm owner convicted of a felony couldn't lawfully sell his weapons on the open market, or transfer them to an independent third party. Today, in a crisp eight-pager by Justice Elena Kagan, the Court unanimously ruled in favor of the firearm owner. Along the way, the Court ironed out some significant legal wrinkles. Of special note, the Court clarified that felons can be entitled to the benefits of equity in federal court.

When an individual surrenders his firearms to police and is later convicted of a felony, what happens to the firearms? The weapons can't go back to the felon, because federal law prohibits felons from possessing firearms. Yet the felon still owns the weapons, which could have considerable financial, sentimental, or historical value. Understandably enough, many felons in this situation would like to sell or transfer their firearms, rather than let Uncle Sam indefinitely possess them. The question before the Court in this case was whether federal law gave felons that right to transfer.

In the decision under review, the U.S. Court of Appeals for the Eleventh Circuit had ruled against transfer based on a broad view of "constructive possession" - roughly, the idea that someone can lack physical possession of an object but still exert enough control over it to count as possession for purposes of law. The court of appeals had also seemed to say that a convicted felon lacked "clean hands" and so could not take advantage of any form of equitable relief, including equitable transfers of property.

Today, however, the Supreme Court unanimously ruled in favor of the firearm owners by allowing them to transfer their weapons to independent third parties, including to have the weapons sold on the open market. As Justice Kagan succinctly explained, this is a pragmatic solution that accords with the statute's text and purpose, and also has the benefit of fitting snugly with common sense.