The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . 
I don’t think you can find Hydroxyelite at GNC. In my opinion the best place to buy it is at Strong Supplement Shop – Hydroxyelite . Strong Supplement Shop ships same day and you will receive your order in 1-3 days depending where you live in the US. They always have up to date fresh stock as they buy direct from the manufacturer, they are the largest retailer globally for Hydroxyelite and many other supplement products. Plus they have an onsite customer support staff of trained bodybuilders, trainers and athletes who can help you with how to get the most from your purchase or with any questions you might have about your order. Many of the products they sell are professional use and not widely commercially available – they are a good source for what is new on the market, what works and comes from large and reputable manufacturers. Oh yeah, they also have good prices.