@Virginia Heidinger the problem is the laws vary tremendously from state to state, sometimes from county to county. The laws can change from year to year. Maryland has changes almost every year. (I just got off the phone with a State senator about tax sale) This means that any national course won't have the detailed information you need.
A book often recomended is "The 16% Solution" I am sure it will give you the basics. There is no harm in buying a $500 to $2,000 course if you can afford it. But realize that NO course will give you all the information you need. Most courses are specifically designed to drain your pocket to the greatest degree possible and then upsell you. Many of these courses are carefully crafted manipulative scams to get you to buy more. Some will actually provide misleading information.
Consider this, how much time and capital will it take to recoup a $25,000 course if you are earning 6% returns? While I have hear the 16% solution is a good book, it has been a long time sice tax sales returned that much. I see tax sales bid down to 4% or less regularly around the country.
The people who do this well, read the state and local statues and study how the rules of any given auction afffect their costs and returns. We have a number of experts in particular states that post here regularly for free.
Be aware tax sale definitly has risk, the returns are not guaranteed, and it is not as passive as those promitiong it would have you believe.
You can do this! You cannot just buy a course and expect it to be easy and profitable.
