Hello,
There is one I found on Ebay with a 10yr warranty for $36.95 and free shipping. I got one for my 24" round, but haven't used it yet, so I can't say how well it will hold up, but if they honor their warranty if it does tear up then that's a plus.
Plus with Ebay's Money Back Guarantee, you can't go wrong there because If the company doesn't honor the terms of the ad, EBay will refund your money to you, and then EBay will go after the seller to get their money back. So that's why I decide to give it a try. Plus the price is like 40 less than most other ones I've seen.
As far as the pillow a lot of people do use them so the water doesn't collect and weight down in the center of the cover. That is your choice to use it or not, but something under there is convenient to allow the water to run off the cover better, and keep the water out of the center. I actually used a couple of blow up floats in my smaller pool that I gave a couple dollars for at the Dollar Store, and they worked well. Depending on the amount of rain/snow you get during the winter you may still have to break out the shop vac or something to remove water off it to keep the cover from sinking into the pool, or when you get ready to uncover the pool next season, but any little bit helps for sure.
Also a tip I use that works great to help hold down the cover is to place clothes pins about every 6"-12" all the way around the underside of the frame and clip the cover to the frame.
Here's the Link to the cover: http://www.ebay.com/itm/16-Round-10...7695b2e&pid=100204&rk=4&rkt=4&sd=201355748712
I hope this helps, and have a wonderful night.