averageif criteria when the range must be within a set distance of a cell's value

Hi all,

I'm trying to use an averageif formula to return the average of values in column E in cases where the values in column C are within 400 points of B2. So the average over values of column E is taken only if the the absolute value of the difference between B2 and each cell in C is less than or equal to 400. I was wondering what the necessary command might be.

=AVERAGEIFS(E:E,C:C, ??within 400 points of B2??)

would really appreciate yourhelp, I'm realy stuck and I'm sure it's not that complicated!

Thanks NBVC!