Well I know airports which are off limits for jets, but do not know about any ruling single turbine out if they are above 2 tons.
Are you sure this new owner knows what he wants?
Early CJs are now trading for about 1 million. Only the fuel expenses will be higher compared to a TBM, but the CJ is much faster. Airway and landing fees will be in the same range.
And if you ever loose one engine there is a big difference!