I discovered this fairly long list of ghana-related NGOs that might be of use to someone researching volunteer placements:
http://www.ghanaweb.com/GhanaHomePage/directory/cat30.html
click on 'foreign' or 'local'.
I can't vouch for any of these but perhaps you'll find some alternatives to the bigger names in the business.
It goes without saying: take care paying any money in advance - most will happily take your money once in Ghana.
also check out www.uvo-ghana.webs.com . i can personally vouch for this having visited twice and working now as international coordinator. its a very friendly country and our project is very grassroots, very well run, cheap and progressive. all returning volunteers have had a great experience, join us on facebook at 'uvo tafo' to chat...
Just submit the NGO details to the GhanaWeb directory.
By the way, why does it cost more to volunteer with you than it does through these people: http://www.kidsworldwide.org/ghanakwahutafo.htm ?
It appears to be exactly the same project.
Great link! You can also check www.unitedheartschildren.org. It is community run project with very affordable prices!
I think a great organisation to volunteer with in Ghana is God's Glory Children Foundation (you can find them on facebook at http://www.facebook.com/pages/Gods-Glory-Children-Foundation/228493737214708) They specialise in the areas of Education (and I volunteered as a teacher at Maranatha prep school [www.maranathaprepsch.com] for 3 months - it was amazing) and you can also volunteer in the area of Health. But they are open to any suggestion you may have on what you would like to do .