First of all, based on the price, it sounds like you are talking about "UPS" as in, walking into a UPS Store, giving them the wheel, and paying them not only for shipping, but also for the box and shipping materials and for them to box it up. That's the most expensive way to ship but lets them do all the work. You can save a lot of that by doing the packing yourself, and you don't need any access to special discounts. What you need to do is:
1. Get the size box you need for shipping, which you can probably do for around $3-4 at Office Depot, around $6-7 at Staples or the UPS Store. Interior dimensions about 1" larger than the outer dimensions of the wheel itself - and remember, the outer dimensions are about 1" larger than the nominal dimensions which are taken at the bead, where the tire sits. For example, a wheel that is labeled 16x8 is typically about 17" in outer diameter and 9" in outer width so you would need an 18x18x10 box.
2. Get whatever packing materials you need for it. For wheels, I like to put pieces forming an extra layer of cardboard around the edges of the wheel and on the face of the wheel. I get free used display boxes at the registers at Costco/Sam's Club and cut them up into the pieces I need.
3. Pack it yourself, and pay for shipping on the website for USPS, UPS, or FedEx, using their rates for dropping it off at their nearest facility (post office, UPS Store, or FedEx/Kinko's), which will give you the lowest rates. UPS and FedEx give free insurance for $100, you can pay extra to insure for more.
You can compare rates on their three websites to see which is cheapest, which is not usually UPS. Just to take an example, here are standard rates according to their websites for ground shipping a 24-pound package 18x18x10 insured for $200 from zip code 30301 to a business in 90210:
FedEx $37.40
UPS $42.05
USPS Standard Post (formerly called Parcel Post) $38.19