Electrical Box Trim for Vinyl Siding

[Zero102]

Where can I get a replacement one of these?
Ours has gone all brittle and shattered. I went to home depot and rona and tried to explain what it is to the guys there and they treated me like I'm some kind of idiot asking for a thing that doesn't exist. I expect I'll have to buy both halves of the trim piece and that's fine if so but I just need to know where might actually have one.
In case it's hard to visualize what this used to be from my shitty picture, it's a ~6" square plate that fits around a 4" round pancake box so you can mount a light on the outside of your house. My google skills are completely failing me so I can't find a comparable picture of an intact one.

http://i.imgur.com/2FUk8UG.jpg

[infected]

Do you have some spare/extra siding left over? Can you cover the existing location and then use a mounting block overtop?

[kenny]

Tell them you are looking for flashing to fit around a 4" pancake box

At least that's what it sounds like you're looking for.

[Zero102]

Originally posted by kenny
Tell them you are looking for flashing to fit around a 4" pancake box

At least that's what it sounds like you're looking for.

That sounds like exactly what I need, but neither Rona nor Home Depot had anything that would fit. Any idea where I could get something? Should I be hitting up siding stores or electrical stores... or...?