Sorry, that was $17.99 + $3.74 shipping
Whatever slippery synthetic underclothes you choose, be sure that you can snugly adjust the belt on your riding pants. Suspenders might also be a good idea.
I lost a bit of weight and my Firstgear riding pants were a bit loose at the waist. With slippery underwear and slippery pant linings it was most annoying to have to hold my pants up when off the bike. I suppose that many of the ladies don't have this problem with their waist to hip ratio.