Sourcing medical equipment is an important task for people such as physicians, doctors and organizations such as refurbishers, manufacturers, dealers and leasing companies.
Some websites specializing in locating medical equipment, both new and used, will carry catalogs... both online and physical catalogs. Subscribing to several catalogs will enable you to locate the precise medical equipment you're looking for as well as give you a comparison on the prices for the items, shipping costs and delivery times.... all of which can vary tremendously.
You can find medical equipment supply sites from the big directories such as Yahoo and DMOZ as well as from searching directly at Google for the precise item you're looking for.
If you're interested in buying your medical equipment items in bulk, you may want to search for sites that offer wholesale pricing. The wholesale rates may be listed on the individual sites, or they may be something you would have to apply for, or be pre-approved for. The same goes for volume discounts.
If you are outside the US, you will need to check whether the site you are considering buying from supplies goods outside the US, and what the shipping /delivery costs will be.