Yes — a DSLR shutter can usually be replaced, and it’s a fairly standard repair. Based on the community replies, a typical shutter replacement cost is about $200–300.

That said, the 100,000-actuation figure is a durability test rating, not a hard expiration point. A shutter may fail earlier or last well beyond that number, so there’s usually no reason to worry in advance. If you shoot around 1,000 photos in some weeks, you’re still likely looking at years of use.

For an older body like the Nikon D5000, the bigger question is cost-effectiveness: when the shutter does fail, the repair bill may be a large fraction of the camera’s value, so it can make more sense to replace the body instead of repairing it.

Bottom line: don’t treat the rated shutter life as a countdown timer. Use the camera, and if the shutter eventually fails, compare the repair quote with the cost of a replacement body at that time.