Sealed can range from $5+. Really depends on the size, shape, and amount of chambers.
Ported: $20-30, the more complicated, the more expensive.
All kerfs and flared ports are automatic $30
4th order bandpasses, 6th order bandpasses, t-line's start at $30 and usually stay there. Sometimes there is a $5-10 extra if you want a lot of extra work, like a bunch of plexiglass, terribly funky shapes, or a massive flared/kerfed port.