I don't think Urban Jungle sells mulch, unless it's some precious tiny bag of something for a terrarium that costs $25.

EDIT: I just remembered that they now have a nursery at Morris and Water Street, but their web site says they are still closed for the season and does not give an opening date. I'm assuming they would sell mulch there along with their outdoor plants, but I haven't managed to check it out since it opened so I can't verify. https://www.urbanjunglephilly.com/nursery