It really depends on the parent stock and generation. I haven't seen many that had good orpington type. I know a few months ago they were selling for 20.00 a chick. I'm selling them for 10.00.
They are no longer, "rare," as some like to advertise. The are also not true to standard Orpingtons yet, either. Their value (price) or worth, is whatever you want to pay for them. They still need work, and should be bred back to black Orps to continue the project.
I see many selling them for outrageous amounts, and they are not even working on the project. They are just trying to make a buck off them. All you get from them is the Lavender gene in a chicken. The work is then up to you.
Ditto with previously said. Most are just Lavender chickens not Orpingtons, and to me, worth no more than $5 per chick but people often pay quite a bit for them despite their rising common finding.