A quick look on google returned the opinion that a D50 should be good for 25000+ acutations. There is no definate figure on how many clicks at camera will do but it seems to me that 3000 on the D50 you have been offered is low.
You'll find differing opinions on the net regarding the lifespan of the D50 ranging from about 10000 to 50000. Quite a few suggest it to be around 30000 - I wouldn't argue with that, after all it's not a pro grade camera. You'll see plenty of users getting 60k+ some will get 11k.
I would say it depends on all sorts of things like where/how it's been used. If you use it in a studio all day then I would expect something at the high end. If like me you throw it around and shoot at wet windy locations getting it covered in sea water, and constantly changing lenses, throwing it in the back of the car etc then expect something at the lower end.
My D50 has done about 10000 frames - maybe the end is in sight?