I added the extended distribution package as part of the normal costs and left it at that.
The royalties drop when the book sells via a third party--say a bookstore orders copies to sell.
I get about 1.00 per copy through third party and library sales. The rest of the time it's 25% royalties on a 14.00 trade size soft cover.
That same book with a commercial house would get me 8% of half the cover price. So even at 1.00 per sale I have better earnings.
HOWEVER-- for each print copy sold I sell 30-40 e-copies.
Last month I'd sold 2 print copies and 1 extended distribution copy.
I make a 70% royalty on the ebooks, so I can sell at 3.99 and still make more than the print book.
The other HOWEVER for a print edition:
Since it is self-published, bookstores and libraries are not likely to order it. You might get 3rd party only booksellers, but that's about it.
I saw one had my title on his e-store for about 50 bucks. He must be hoping that someone spots my name and misses the 14.00 and 3.99 copies right next to it in the listings.
My advantage is that I'm commercially published, have been for 20+ years and when a reader looks for new titles on Amazon or B&N the self-pub books appear on the results page. I have the Look Inside feature and first chapters on my website.
I'm not discouraging your getting the extended distribution, but unless you're certain you'll be selling a lot of copies--for me, 5-10 are a LOT of print copies!--it's probably not cost effective.
Perhaps other writers who promote more sell more. I'm pro published, and a damn good writer, but sometimes that's just not enough.
I would suggest holding off until you've earned that 25.00 in print sales, then put that money into the extended package. That way you stay in the black!