I have heard and seen several re-use the stock lifters. They are roller and dont so much wear to a specific cam (I have heard they like a specific hole in the block due to the wear in the bores though).
If they are not holding press. or marked up from the bores or something replace...otherwise no reall need. If you have the extra $$ and are not sure go for it.
i suggest replacing them if your in there to do the cam. i cheaped out when i did my heads/cam... only to have two lifters fail because of the extra lift and spring pressure. had to tear my intake and stuff all back off to replace mine. IMO spend the $120 for all new ones and not worry about them