You don't say whether you are a driver or an inside employee. In our center, the baseball-style hats are given only to the drivers; however, you can order UPS merchandise from our employee website, UPSers.com. Go to "Our Company" and then click on UPS Merchandise, which is on the left side of the page.
Yeah, that's what we did at our centre as well. When I asked for an official UPS hat from the uniform list, the thing they gave me was so ridiculous looking that no self-respecting person would be caught dead in it! I mean, that thing would fit a basketball!
So we asked around at local embroidery shops and found one to make us some hats. Baseball-style with adjustable velcro straps. $8 a piece or so because we bought in bulk.