Buying land isn't something that can usually be done inexpensively in Los Angeles. The auction is held twice a year and minimum bids can be quite low.
When looking at properties in the Los Angeles County auction, your new favorite website is going to be the Assessors portal. Here is the link: http://maps.assessor.lacounty.gov
Zoning and size are the two most important pieces of information you need on each property in the auction to determine whether to proceed with researching the property.
Usually, there will be a document available that lists parcels with known issues but, it is your responsibility to do your own due diligence on a property even if they don't list issues with it.
The research stage is the most important part of buying properties at a tax auction. Do your research before you buy and you could potentially end up with a quality gem for a very reasonable budget.