do what you want mate, its your car

if you pay a garage to do it for you i think your probably looking at 1500 - 2000 + the price of the parts..
the parts could cost you 1000 - 2k alone..+ uprating things like brakes/ suspension e.t.c to match the new power...

or have a crack at it yourself, if youve got basic knowledge its pretty straightforward once you get into it.

would be easier if you had the donor car and your car side by side though so you know your not missing anything e.t.c..
then once its all done get a garage to check it over