The answer to this question poses many more questions, such as what are your interests and specialties? If you are looking for an established product line you could become a consultant for any one of the many home party programs. The majority of these require a fee for the start-up kit, but they are rarely over $500.00.
Also, if you like working with numbers or in an office environment you could purchase a bookkeeping and/or office computer program and contract your services. The two of these programs are usually available for less than $500.00 combined.
Another option is a kennel if you enjoy dogs and cats; a couple of dog runs and dog houses could easily be purchased for under $1000.00. As your business grows, you can invest some of the profits back into additional facilities for the animals.
As I've said, you have to do a bit of self-analysis to know what direction you wish to take. The possibilities are endless once you know what types of things you like to do. Good luck!