I know this is an old thread, but wanted to post this.
I've been into weight lifting for 5 years now, and there is a whole bunch of new "products" that have come out, to increase muscle mass and the like. Technically they are all legal, because they are for "research only", and "Not for Human Consumption." PDE5 Inhibitors - Ancillaries
Everything on this site is Good to Go. They advertise on steroidology.com, and elitefitness.com. and others i'm sure.
The products on the link I provided, are the liquid forms, of their respected pill counterpart. Viagra, Cialis, and the other one.
I have tried them, but not for the purpose of enlargement. Not to say it wouldn't work, because I don't know. But, if it allows, more blood flow to the area, who knows. I am in no way shape or form affiliated with any of them.
There are many other companies, with different prices, Greatwhite peptides, ag-guys.com