This all depends on esters...I'll try to make a simple outline for you here, a "cheatsheet" if you will, let's assume that the homebrewer knows what their doing and is making a concentration that is almost 100% sure not to crash:
(if anyone disagrees feel free to chime in)
Traditional Formula: 2%BA/15-20%BB/oil carrier
Acetate ester: max concentration = ~100mg/ml
Enanthate ester: max concentration = ~400mg/ml
Cypionate ester: max concentration = ~300mg/ml
Propionate ester: max concentration = ~150mg/ml
Phenylpropionate ester: max concentration = ~200mg/ml
Decanoate ester: max concentration = ~500mg/ml
Undecanoate ester: max concentration = ~600mg/ml