On this question, I usually suggest people contact a nearby independent carpet sales & installation company.
They often do the installation thru a local independent,
who is usually able to stretch already installed carpet as well. Ask to be referred to this person.
In my area, carpet stretching ranges from 2.50 to 4.50 a yard depending on if there is furniture to be moved. I used to have a helper who could kick wrinkles out fairly well, however he no longer works with me, and I never wanted to learn the technique as it looks experience heavy, and also requires knee kicking which could damage your knee.
