The White Baseboard Return Vents have both the price and durability you have been looking for. Made with the traditional white enamel coating over steel. Baseboard returns do not have a damper.
 

Rectangular Baseboard Register has a fully adjustable damper, giving you complete air flow control. This white baseboard register comes in choice of horizontal or vertical fins.
 

Triangular Baseboard Registers are available in white, brass, or oak. Use for new construction or to replace those tired out triangular baseboard registers. Sizes up to 48 inches.