Cost effective? Yeah, they're FREE!
Aside from a little electricity, (probably no more than a coffee pot left on for several hours), and the "search" for lead, there's really no cost involved after the equipment is purchased.
The moulds, pot, and sizers are the most expensive part, I pick up wheel weights from tire shops, I've been real lucky in the past and they usually just give them to me.
Wheel weights aren't the "best" bullets, but for plinking, you really don't need "match grade" bullets.
As for the Lee casting pot(s), well, they're alright I guess, but I think if you can afford a higher end model, you might be better off in the long run. When this one finally dies, I won't be replacing it with a Lee, if that's what you want to know.