Using a buyers agent like me who specializes in 'deals, " especially in the city, is a good start :)
I know that area extremely well and have previewed most of the current MLS inventory, and have other leads in that area. You may reach me at firstname.lastname@example.org or 314-766-0847.
Now, for the really really great deals, stand in line. The Realtors and the rehabbers know the areas and are watching for those and often if they go to list a home that is a great deal, it never makes it to the market, it's snapped up immediately. I have a list of rehabbers and investors and buyers I'm working with, as does every agent I know. We're all approached daily by multiple people asking us to watch for that perfect sweet deal for them and let them in on it before anybody else gets a chance at it. If you've got a good relationship with a Realtor and they don't feel like they are being used for the information and then you will break away and buy it through someone else cutting them out, they will work with you, but too many have been burned by people who used them to do all the research for them and find the sweet deal then bought it without them, so unless they think you are truly going to work with them, they are not going to go out of their way to help you. Keep in mind that Realtors are only paid after they successfully help someone find and close on a home, we are a totally commission based industry and on a sweet deal for you, the commission isn't much in the first place. One other comment - once an area is "HOT" like Tower Grove is right now, finding a great deal there is a lot harder. Look on the fringes of the area, or look at the other areas which are just starting to be fixed up and aren't "HOT yet.
By the way, I've been researching that area recently for a buyer who is moving back to St Louis from out state. There is a bit on the market in that area, but it moves quickly. They would send me a list of ones they wanted to see and half would already be under contract. Consider when you say that you want a foreclosure or auction home, how much work do you really want to do to it? Homes in that category are typically going to need work. Are you prepared to do it yourself? Do you know how to look at a home and judge how much money it will take to fix it up? Will you need to hire contractors? If you hire contractors your sweet deal could get a lot more expensive pretty fast, depending on how much work needs to be done. Make sure that you have a good building inspection done, the older buildings have a lot of interesting issues at times that an inexperienced inspector won't catch.
Good luck. If I can help in any way, please let me know. That's a lovely area and the property values are climbing there.
Your best bet is to contact a local Realtor and have them locate a property for you. It is my experience in San Jose, that you can get a pretty good deal before properties go to auction. Sometimes folks are paying more than what homes were listed for at auctions. When you have a couple of thousand people in a frenzy to buy a property you never know what's going to happen.
Best of luck finding your home!