A highlight of my trip to Laos was the gibbon experience.

I was in Laos September/October last year (still can't get over how insanely beautiful that country is), and seriously thought about doing the Gibbon Experience, but ultimately decided against it due to costs. The prices I found for 2d/1n were much higher than the 170 you paid - maybe prices are seasonal or lower because of the large group?
So instead I went to the Elephant Conservation Center in Sayaboury (about 2 hours by minibus from Luang Prabang), which was an absolutely terrific experience as well (witnessed the first-ever attempt to do the naughty by a newly matched potential breeding pair :D), but after seeing/reading this thread, I might return one day to visit the Gibbon Experience after all.