Gh levels vary by age....

When you get bloodwork done, you will find your own levels, and usually there is a range provided of healthy values. It's a bit of a moot point. No matter what your levels are, GH bodybuilders will add to it for the increase in muscle.

I just want to know how much more we're taking compared to what the body produces. Also, if only so much IGF's is being used up by the receptors does that work the same with AAS? That the rest will go to waste?

The mechanism of action of AAS and GH is different. Whilst AAS will produce hypertrofy, meaning the increase of muscle cells, GH will produce hyperplasia, the developping of brand new muscle cells. Technically there is no limit as to effectiveness, meaning if you do 100 cycles of GH, the 101th will still provide results, although probably less than before. Assuming you use GH for bodybuilding, some reasons to stop using GH are budget (gets expensive); cosmetic (GH gut and unaesthetic growth of basically everything); and health (growing of internal organs).

I believe that at age 20 500 mcg of HGH is produced by the body, 200mcg at 40yrs, and 25mcg at 80yrs of age