Just need to realize that it would be "extremely" rare to only do the headgasket. Does the engine smoke a bit? Maybe the head should be gone over by a mechanic regarding valve sealing, oil seals, flatness check, etc. Everything involving the timing belt (with tensioners/idlers, cam and crank oil seals, water pump, oil pump, etc.) is there and it may be time for that. What condition is the turbo in? Valve cover gasket and spark plug tube gaskets. Spark plugs, distributor cap & rotor, spark plug wires, distributor o-ring (oil seals). Many hoses become accessible with the turbo removed - they get baked by the heat of the turbo & engine - maybe hose are hard/cracked and need replacement. Intake & exhaust manifold gaskets and other gaskets associated with the intake & exhaust systems. I can go on, but you get the idea. Some must be replaced - others it is a choice (pay me now or pay me later). Up to the owner on what is best.