This is a tough one to be honest. It really comes down to a trust issue, and there are VERY few people id trust with my pride and joy in N.Ireland. I ended up going with DubTec in Ballymoney for my stage 2+ map. Hes a Revo dealer and he must have spent at least an hour on my car with VCDS after he put the map on, to get the settings right. Then you have the support of Revo behind you as well.
The only other person id take my car to is JW Service Centre in Coleraine. They use Quantum Tuning. These are the guys that I take my car to for any mechanical work also, such as servicing etc.
I would caution you against looking for "best prices" when it comes to remapping your car.