Is there not a redemption period? Not too long ago in Colorado it was common to not pay taxes and invest the money instead. The "loan" from the county was at something ridiculously low number and people were making more money than that. Someone would buy the tax cert, and then be disappointed when the owner would show up a day before the expiration and pay it off. The guy that bought the cert got 2% for his money while the owner returned 10% (yielded 8). Some friends bought the cert on a local notorious a*****e but he paid it.
I think you may be referring to a Tax Lien Sale. These sales are conducted by a governmental agency in the county for which the property taxes are delinquent, and you are correct regarding the redemption period. The investor must wait until he or she can see a return on their investment including penalties, late fees and interest. Once the time period has expired (every state and county is different) the investor who owns the tax liens then can initiate foreclosure.
At a Trust Deed sale, the deed to the property is being offered for sale. Once the investor purchases the deed to the property they can do what they wish. (NOTE: I am referring to California). Generally it is the bank that initiates the foreclosure process (there are several steps, but I’m giving you the “Cliff Notes” version). The bank is foreclosing on the Note due to lack of payment however in most cases (all cases I am aware of…. again I am referring to California) the bank will make sure the property taxes are current on the property for which the mortgage is attached too.
As an investor purchasing at Trust Deed sales, it is wise that you have a network of people working with you. Most importantly you want to work with a title company who can provide you with title information as to how many loans are on the property and which loan is being auctioned. Unfortunately I have known people who did not do there due diligence and purchased (or so they thought) property at the Trust Deed sale only to find out that they are the proud owners of the 2nd or 3rd mortgage.
Do your homework and you can get some really good deals!!!
; and then the electricity can be $100-200 month depending on system type. 
