I have two very high quality porcelain, dry-erase whiteboards (school-grade quality). Porcelain is vastly superior to melamine (the cheap white plastic kind) and will basically last forever if you don't gouge it with handtools. With porcelain, you get a clean erase every time, and with steel below, you can use magnets on the surface to hold up pieces of paper or even your dry-erase marker.
Purchased from this site (model is very similar): https://www.schooloutfitters.com/catalog/product_info/pfam_id/PFAM50433/products_id/PRO73170 (Currently $650 each.)
Please note: These are 4 by 8 feet; they are heavy (website say 71 lbs each). Please make sure if you buy one, you can fit it in your transportation. They are currently in a garage on the ground floor, so they are easy to access. I can help lift and place in vehicle.
Can include some starter markers (and eraser if I still have any).