I just order the King sized TQ from Wilderness logics for $225 shipped. They also have a new full length UQ for sale, and offer a discount for the pair. The link to a review I read is below, it may be of use. It helped me make up my mind to take the plung and give a TQ and UQ a go. I have a thread started on the UQ forum section for the full length underquilt. I will post pictures of the goods when I get my package.
Im 6'1" and 280-290ish. My regular bag is a Western Mountaineering Badger 6.6, I paid over $400 for it some time ago. Its 42oz, rated to 15 degrees, and is one of the best purchases I've ever made. The bag is of very high quality, which is a good thing for that kind of money. But for the cost, it still runs tight in my shoulders, and is a pain to wiggle in and out of at night, or try and zip closed.
The WL bag is 25oz, rated to 20 degrees. And according to reviews I've read about their stuff, well worth the money, and at about half the cost! Plus, its made specifically for big guys! Most folks on this forum swear by top quilts for comfort and ease of entering. It was one of the main reasons I'm giving it a shot. Hopefully, someone else may chime in that owns a King sized TQ from WL.
Another option to buying new is buying used, and watching the sale thread. There is also a sale menu on backpacking light that has top quilts listed often. TQ's come up for sale mostly when someone buys a newer bag and want to sell the old, or when folks try something they decide isn't for them. The problem you may run into is getting the "long" version most makers call their bigger size. My issue is, while they are often 6 inches longer, not all of em are much wider than another two inches. I'm hoping the King Size WL TQ does the trick fro me.