A good rule of thumb for handling is to use the smallest diameter wheel that will fit over your brakes. The rotational inertia of larger, heavier wheels will hurt your acceleration and braking. The unsprung mass will adversely impact the suspensions ability to keep the contact patch on the pavement.
Within a given size lower weight will be more expensive. A good explanation for this and many other wheel/tire related things may be found here:
A good example is the wheel in my avitar. It is 16x7 and 11lbs it is also over $325 but, makes a very noticable differance from the 21lb wheel it replaced.