I would strongly urge you to build your credit up first. Depending on your reason(s) for a low score, you could
possibly do want you need to do to significantly increase your score over a relatively short amount of time and little expense. I currently have a buyer that got a 43 pt boost in her score by simply paying down her credit by 384.00! And it took less than 5 days to do it.
Heed my advice, have a knowledgeable LO look at your credit and determine want you specifically need to do. The consultation itself should be free and you'll save yourself thousands of dollars in extra closing costs and higher interest rates.