I think it's highway robbery, the prices those sewing furniture places ask.
Take the "sewing" out of the description and think "table". Costco sells a nice 6' long table that is height adjustable. A sturdy desk is nice and has the added perk of drawers. Tables/desks come in a variety of shapes and styles, you could find the perfect one for next to nothing.
My first sewing table was my son's old computer hutch.