The other option is, you can use your assets, if you have,  to supplement income requirement . If you don't have such assets, you will need to find a joint sponsor who would file form I-864 for your spouse. The sponsor does not have to be related to you, he/she can be your friend or employer. The sponsor will have to fill up the same form you file. Remember, even if you don't meet the income requirement and have a sponsor file for your spouse, you must also file I-864.