If you want to learn a bit about the joys of designing magnetics, you can have a go at making something yourself, particularly if you have some kind of old steel core transformer that looks like you might be able to pull it apart. Unfortunately, they are much better at impregnating the steel leaves with varnish then they once were, so pulling the leaves apart with modern transformers is hard.
To handle the DC current and to maintain a constant inductance over the DC current range, the transformers has to have a gap - something normal mains transformers do not have. So you have to rearrange the E-I leaves so you can have a gap (all the E's together, all the I's together.) I think it has to be a steel core to handle the DC at a high inductance. Ferrite cores will just need too many turns.
Then you get to the fun mathematics to find the minimum gap, and from that the number of turns, and from that the size and resistance of the windows. Easier to buy an inductor, but if you do have to make something, you can end up with an inductor that performs well.