Lourdes,
A minimum cost would be around $4000. The cost of the engine is just the start, all the items you mentioned increase the cost dramatically. I'm finishing up a Facet 2300 that I scratch built using up some of my balsa and ply stock and I'm using my Monokote stock to cover it. Not counting the cost of the wood, which I bought years ago at much cheaper prices, I have about $3600 in it. If you go with a 'Roo type model, figure another $800 or so for the plane and retracts.
Of course you go to the used market but unless you know the person you're buying the engine from, you'd probably send it back to the factory for a check and make whatever repairs are necessary, so I'm not sure you'd save that much, plus you'd have a generation or two older technology.
I can see why some turbine fliers say they never relax or have fun when they fly because they're afraid they'll do something stupid to wipe out their investment, and for some this is a one shot deal, if they crash they're done with turbines.
A rule of thumb BV told me was if you can't shrug off a crash with whatever class of model you're flying, your in too deep.
Regards,
Jon