Apart from the risks, penoplasty (surgical penile lengthening and girth enhancement, often by releasing the penile suspensory ligaments, so just an optical improvement) is the most expensive way for penile enhancement. According to About Health it ranges from $4000 up to $17000. If you are interested in surgical enhancement, we recommend reading the in-depth article on Medscape about possible surgical techniques and results. There is a less risky new method, the FDA-cleared Penuma implant developed by my collegue Dr. Elist (James Elist, MD) for flacid size enlargement, but the erect size lengthening is minimal and the cost is in the low five digits, too.
Lengthening the penis. The most common procedure is to cut the ligament that connects the penis to the pelvic bone. This allows a little more of the shaft -- on average less than an inch -- to become visible outside the body. It's not really lengthening the penis so much as revealing more of what's usually hidden. To prevent the ligament from reattaching, a guy would need weights or stretching devices daily for about six months.