Hi, Snoonie, and welcome!
Trafford is a subsidy publisher, meaning that you WON'T be self-published. Self-publishing requires that you ARE the publishing company. You handle each individual detail, such as buying the ISBN, designing the book cover, paying the bills, etc.
That said, frankly they're quite a bit more expensive than many other subsidy publishers, although they do produce an acceptable product. However, you won't ever find one of their books in your local bookstore, since the product is not returnable.
Here's a thread about Trafford in our Bewares & Backgrounds forum. You need to decide what you want from self-publishing. If you don't mind doing all of the work to prepare and market your book, there are less expensive options from printers who won't lead you to believe that you'll be getting something you won't actually receive.
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Good luck!