Oral - dutasteride or finasteride (unitedphamacy.com)
Topical - Minoxidil 5% (just search even walgreens has it)
Shampoo - Nizoral 1-2% (tons of places online. Some stores have it. do a search)
They also have actual stores/chemists. To be honest you can probably get the products from any chemist, I just use epharmacy cos they are quite cheap.
So yah the big 3
1) Propecia (finastride) Need a prescription from your Doctor to get this. Take 1mg once a day. This lowers DHT levels in your blood, thus you hair follicles no longer get attacked by it and balding process stops/slows and you might probably get regrowth.
2) Minoxidil liquid - there are several brands. Probably get the Rogain/Regain brand since money is of not much concern to you. You need to rub it into your scalp in the area that you wish for better/more hair twice a day, morning and night. This promotes hair regrowth/maintenance, but your hair follicles continue to get damaged by DHT if you don't use a drug like Propecia.
3) Nizoral shampoo - 1 or 2% - I don't really know which is better, but I got the strongest. I don't think this stops hair loss by itself, but it promotes a healthy scalp.