yeah, like that, but the sizes vary away from that
http://www.thebookpatch.com/
http://www.blurb.com/trade-books
https://www.createspace.com/Products/Book/
http://www.lulu.com/create/books
https://www.lightningsource.com/shippingcalc.aspx
I would personally stay away from sizes that are like 5.06 x 7.81, but I think the 4.25 x 6.75 is the size of those mass market paperback books (those cheap, tiny books you can find for $7.99)