all depends on your modus operandi..
a, you buy lots, sell lots and make a few $$ each time, or,
b, you dont buy anything you wont sell for min $$$$
Advantages and negatives for both, im a B person but most are an A.
One thing thats not worth it is sell one or two domains and make $5 e.g..
To be an A you need a lot of domains and a lot of turnover to make a profit