Umpiring is probably the most expensive sport in which to start officiating. Between uniforms and equipment, the cost can run from a couple of hundred to well over five hundred dollars, depending on the amount and quality of equipment and uniforms you purchase.
"Starter Packages" for beginning umpires are available from most vendors. These are generally basic packages, but they have just about everything you need to get started.
Equipment can be purchased from a number of vendors. Check the LINKS page for a few of them. There is one local vendor (shown below) where you can purchase Official MOA uniforms (Shirt-Jackets).