I would recommend an actual garden store as opposed to a Loewes. Surely Denver has one or more of those? Try
Welcome to Paulino Gardens | Denver, Colorado They are located on Broadway and appear to carry coir, CHC, bark, and several grades of Perlite. Check under the Hydroponic section on their website. It is truly amazing what the internet can show you if you just let your fingers do the searching!
Orchid potting media is more a specialty item in areas like yours and Lowes tends to cater to the average gardener. Google 'Garden Supply in Denver, CO' and see what you come up with.
CL