I just ordered some from Amazon. The tricky part is how much force each strut exerts and where to position the ball mounts. We have a small bed storage space but lifting it bends the mattress, also a Sleep Number, so force is somewhat more than the mattress weight alone. I paid about $35 for the struts and ball mounts. The struts are 90 lb. force and are 17" long. 90 lbs. seems like a lot but locating them closer to the hinge point of the bed platform multiplies the force required.
2015 GMC Sierra 1500
2013 Heartland North Trail 28BRS