Jennifer,
It depends on if they are including homestudy fee, DNA fee, INS (or that's what it used to be, now it's B something), and the fees for collecting the dossier. If so, they are probably close to right.
If they are not including that, then I'd say they are high with the $26,900 they are estimating. I've been looking to adopt again, and Guatemala is one of my choices. I've been finding the fees to be closer to $23k. (that is just for the agency fee and attorney fee)
When we adopted, everything including what I listed above as well as travel was around $28k. Now, I'm expecting closer to $30k because of the agency fee that has gone up.
Good luck in your choice. If you do choose Guatemala, I can say that it's a beautiful country with just as beautiful children. (of course I'm bias

)