Unless you get a smoking deal like a liv2mx is on his motor build, a cam and tune will end up being $800-1000 based on what I've been seeing; more if you push it up and need injectors and and and and
A lot of the cams I have been seeing are $300-400 vs the $150 350 small block cams. If you get enough cam to need valve springs add in a few hundred more. Then if you want some dyno time to get the cam dialed in instead of a mail order tune, add in a few hundred more.
After going through that scenario we spent the extra $300 on the LQ4 to be at least as good as a 5.3 with a mild cam. And we have an upgrade path later.
Having said that my buddy has a 5.3 in his buggy and is happy with it, much better than the 350 TBI it had. But he's keeping an eye out for a good deal on a 6.2...