I'm curious, JP. You do so many removals - the two most competent remover people in Georgia (they clean the area and stuff it with insulation, etc. and guarantee that the bees will not return to that spot) in Georgia charge from $550 - $650 for removals. Do you charge in that range?
My prices vary Linda but if I were Cindy Bee and a beekeeper approached me with your situation, I would do what I could to make it easy on that beekeeper. I more than likely would not charge for the removal.
Without seeing the scenario and scope of the job its hard to say if the price quoted is fair.
Now as far as having a guilty attitude this is just unwarranted and projects negativity but still if its a close neighbor you really never know if they in fact came from one of your hives or one down the street.
All the same, I would still be very involved with the removal process, and whether you like it or not, you are the one with the hives closest to your neighbor and even though they may appreciate your nature and good heartedness, behind closed doors there will be doubt that they did or didn't in fact come from your hives.
Not all swarms make it 1/4 mile or more away, some wind up right next door or on the fence, in the grass, etc... Depends a lot on the queen and how able she is to fly, some can't fly very far.
I have had swarms wind up next door on the fence, and on a tree limb and I am pretty confident they were from my hives. We just can't be there 24-7 and swarming is just what bees do.
Keep positive, it sounds like you have a terrific neighbor. I sure hope Cindy bee gives you and your neighbor proper consideration and gets that price down, way down.
Best of luck,