@Donna Hopkins Welcome to BP. I read through your other posts, so I see you are new to REI and have a successful career outside of Real Estate - congratulations!
Your question is a little like asking, "Where is the best place to eat steak or chicken?" Everyone will have a different opinion.
More importantly is to first figure out your goal(s). Do you want to own property, or do you want an interest return? What is your time frame for expecting your payback? How much time do you have to learn about either? How much time do you have to do the research and due diligence before you buy a lien or a deed?
Liens and Deeds are two very different things. There is a huge learning curve. Every state and even sometimes counties and cities have different laws regarding liens and deeds.
The guru courses only touch on the esoteric differences. They don't delve into the hidden costs. For example in Arizona, you have to wait 3 years from the date of the lien before you can foreclose. In some counties you have to pay the taxes each subsequent year brefore you can foreclose - in some counties you don't but if there is an older lien, that lien holder can foreclose first. There is the cost of sending a certified, properly worded Notice of intent to foreclose to the owners. After 30 days you have to file a foreclosure suit that can cost anywhere from $1,500 to $3,000.
In Florida, if you hold a lien, and the owner has not redeemed (paid back) the taxes, you can petition to foreclose, but you have to pay off the other lien holders, and the county auctions the deed. So you still may not end up with the property.
In Illinois, the type of property determines how long you have to wait until you can foreclose. Vacant residential land is only 6 months. Improved property depends on the type of improvement.
I would hold off buying a guru course straight from the guru - unless you like to pay retail prices for courses and then realize you paid to have the guru company call/email you make a larger investment.
If you want some basic general information, read "The 16% Solution" by Joel Moskowitz. This will give the basics for Liens. If you really want a guru course, go to Ebay and buy one used. The guru won't bother you and you'll have a ton of information. It won;t be local to you, but it will give you some of the terminology.
The actual best way to learn is to go to local lien or deed auctions and just watch. Talk up a few of the investors. Take a lawyer who specializes in liens or deeds to breakfast and you'll get an hour of time for the cost of the breakfast. You'll also have started building your network of professionals. Then, if you have time, volunteer to work with a seasoned investor. In exchange for doing grunt work and helping the mentor make money, you will learn the business from the inside.
Just my opinion. Oh, and if you're in Chicago, I recommend Kinzie Street Chop House for steak.