It depends on what you call a red 2500, and whether you're a collector or just a person who wants a red 2500.
In the order of rarity (and therefore value to a collector) :
WE 1500 with charcoal faceplate
WE 1500 with muted red faceplate
WE 2500 non-modular
WE 2500 modular with translucent faceplate
WE 2500 modular with opaque faceplate
SC / ITT 1500
SC / ITT 2500 with translucent faceplate
all others
In WE, you get bonus points for new in box, or 2500S (speakerphone compatible), 2-line version (2510, 2511, 2515) headset jacks, (2514) Autovon (3500)
Here's a nice 1500D on Ebay:
RED 1500 D
Last edited by Arthur P. Bloom; 05/01/13 07:13 PM.