Start by letting your customers report bugs. Give them an easy way to contact you. Cost will be free. Ensure that you fix the bugs and write some automated tes

Start by letting your customers report bugs. Give them an easy way to contact you. Cost will be free. Ensure that you fix the bugs and write some automated test for this case if possible. Again free. Pay someone to do a little QA of your product. I'm sure it'll hurt to give away money that you could pocket yourself... but it's the price of getting work done.