If the evap really has a leak it needs to be replaced. One hole will follow another and as soon as you get it plugged a new one will pop up. A gas leak leads to low charge which leads to compressor oil starvation and eventual death, so if you are going to keep the car and value a working A/C, do it right.
*If* the compressor has done a front seal and there's no consequential damage from oil starvation, then yeah compressor, evaporator and dryer. Otherwise the condenser and a line flush. I find these new parallel flow condensers are awesome at what they do, but the passages are so small they also act as filters and collect every bit of metal dust that comes out of a starved compressor. There is no way to effectively flush them.
Lots of options and it depends on what you want to spend or what the car is worth to you.
Generally here (In Australia), at workshop rates a new compressor is about $800 (supply and install). A recent quote for a Golf Mk 5 for a new compressor, condenser, dryer and flush was just north of $2k (which is about 2,600 USD).
I recently did the compressor/condenser & dryer in my Volvo and that was about $385 for a brand new compressor, $290 for the condenser and about $75 for the dryer. I did the rest myself.
You guys get stuff considerably cheaper than we do, but 1800 is probably not that far out of the ballpark if it includes replacing evaporator.
Why not buy the bits and change them yourself, then just get the shop to hook it all up, leak test, vac & charge?