I didn't see any prices, but I'll leave you a link to the GF Spa and the Spa at the Disney Institute. From there, there are phone numbers you can call for all the info you need. I don't think the Wilderness Lodge has a spa, as one was not listed on the Disney site. I hope I've helped.
Oh yeah, DH and I used the Spa the GF and had a wonderful time! He got the sinus treatment and lavender bath and I got the facial treatment and the lavender bath! WHAT FUN! I felt like I was DA BOMB that day!