I'd do a lot of homework first, write down what features you want, as this can narrow it down, but be realistic about what you really want.
I wouldn't worry about whether local people can map it, a good map job is worth travelling for.
Remember some ecu's hold more than 1 map so can be used on more than 1 car, simply by plugging in and flicking a switch to the appropriate map for that car/engine.
tabetha