Looking for a longer seatpost but the measurements i'm looking for are pretty obscure, wondering if anyone knew of a place I could buy this diameter. The seatpost fits into the tube via a small expandable bracket which allows the pieces to fit (the seat tube has about 1/2 inch larger diameter than the seatpost).

Measurements: All made will caliper
Seatpost: .86 inches or 21.8 mm.
Seattube: 24mm or .95 inches

Anyone know where I can purchase a seatpost this size? Bike shops around my city all think I can't handle the measurements and ask me to come in so they can measure it themselves.

Bike is a circa 1985 Peugeot road.