It depends on what you mean by 'professional quality', personally I would never by a djembe that has lug tuning, allways rope, djembes from Ghana, Senegal, Gambia, all north-west of africa tend to be good quality. Go there and you'll get one for a fraction of the price you pay anywhere else, plus you could propably find a excelent one...
I payed about 100bucks for my djembe, on size; you just got to go with what feels best for you.