Bitcoin exchange surely profitable, as your exchange rate should be slightly different with other exchanges or else, you should apply withdrawal fees.
For the first time I got into bitcoin, learned how to convert bitcoin and mostly through personal exchange, sell bitcoin to someone based on trust, and he charged like $2 for every transaction. You may want to try it before build a larger bitcoin exchnages which require many resource and professional people to be hired. If you want to build a small exchange web, $2000 is enough to cover initial expenses to establish a legit site, but you will need more to cover maintaining costs.