As Bernd has said, filing and lapping over that length would take a rather long time, plus the fact it is really a very skilled job to get right.
I don't know what the local workshops charge in your area, but I wouldn't expect to get any change out of 100 squid, and maybe a lot more. A cheap rate workshop usually charges 60 squid an hour, and that includes set up times and parts of an hour as well.
You live a fair way from me, I live in Crewe, Cheshire.
If you got the inkling to bring just the bare casting across, I could have the machine ready to drop it onto. The setup and machining should take less than a couple of hours, which means if you got here fairly early (before 11am), you could take it away with you as soon as it is finished.
My charges are rather expensive, a doggy chew for Bandit would just about cover it.
Bogs