As has been mentioned it will depend on your coin of choice. Some services can help you to identify profitability for 24 hour/longer periods of mining. Mining some of the top currencies will require a lot more input up front, this can be quite daunting. My opening rig came in at around $4000 and I've got a long journey until I achieve profit, but it will come.

Of course you have to keep in mind the necessity to release equity that you have vs the investment in the coins and deciding when to sell.