Rockers is an pretty easy upgrade, even if you go 1.9's and upgrade the valve springs as well. Half the cost and work of a cam... But timing and lift on valves remain stock so the benefit is limited as well. Bottom line is it allows just a little bit more breathing.
A cam is much more work, cost but subsequently more beneficial as well. Timing can be aggressive and you'll get a lot more air. To me, in my opinion, you've just got to make a decision on how far you want to go before you start modding anything.
I'm happy with just rockers, headers, ported intake and will do injectors soon. But if I was going cam, I'd go all the way which means, cam, lifters, springs, fluxed and decked heads ported and intake matched, guides, ported intake, double chain, balancer delete, etc., etc. : ).
So you see... You've got to decide what you want ; )