Hi Rick, I take it you've seen this one currently listed on ebay?
http://www.ebay.co.uk/itm/Miglia-Sam...8AAOSwGrFZfMf0
No bids yet at £3k, if I were in the market for such a project I'd contact the seller and see if you can negotiate a price that suits both parties.
As far as actually building a Miglia goes, if your mechanical skills are up to the job of replacing worn out suspension components, brakes etc. on a
classic Triumph, then you would find the build an absorbing challenge.
If you really don't know one end of a spanner from the other then it could be a bit of a stretch unless you're a very fast learner with a natural aptitude for things mechanical.
I wouldn't worry too much about the 'issues' regarding wheel arch alignment and the like, neither the Miglia or the Sammio Spyder that it was developed from are completely symmetrical but nobody ever notices as you can't see both sides of the car at the same time.
If you feel you'll need ongoing technical advice and support, have you considered one of Chris's other Tribute models, like the A352 or D Type? As far as I'm aware, both of those can be built straight onto a Spitfire body tub without the need for a subframe, which would reduce the overall build cost as the bodies are about the same price as a Miglia body. Both those cars also look stunning in the flesh when they're finished to a decent standard.
Anyway, good luck with your project and I'm sure there'll be others along shortly with their own take on the subject.