A business does not run solely on money, it runs on passion. You should enjoy your concept and be excited enough to relay your feelings to your market. You can survive in business without a large bank account - but unless your passionate about your business, no amount of money will make it sell. Your concept doesn't need to be a freshly thought idea - but could be an improvement to an existing market. There are all kinds of new businesses that have tried and failed.
Criticism be prepared to accept all criticism.
It will help you to improve your concept. Because you are concerned about running your business on minimal dollars, the less expensive criticism will come from friends, relatives, and neighbors. It's far better to receive FREE criticism - than to pay for marketing research that puts a dent in your bank account, but doesn't yield any useful results. Be prepared to get LOTS of criticism and to put it to good use. Perhaps, a survey in your intended market - could provide some valuable information to be used in making your product better.