Even though sometimes you feel you are right, consider "losing to win".

@Steve Vaughan I think this is a win- win,  he gets  to keep mom happy  and I should have mentioned the duplex needs about 18-20K to get the 115K .  

The marketers who do will win the game.

Use that to your advantage.I know I am being fairly vague with my answers but that's because you need to approach these sellers with multiple strategies to create a win-win scenario.  

I am sure your client has no intention of doing this.But I have seen these scenerios were this has happened and this is just not about how great it is for you and your student.. both sides must win.

The winning investor wanting to control the property will be willing to pay the delinquent  taxes for the lowest amount of interest as a return on the investment.  

And after some research, I found the majority of the winning bids on the liens go for between 0-3%! 

I think this is a win win scenario and keeps a good client (no late payments) in my property for the second year since their rent just got a tad cheaper. 

I am interested in networking with like minded professionals and doing win win deals. 

I've never had to pay all cash, however in both instances I did use a hard money loan which is kind of like cash in the sense that it doesn't take 20-30+ days for a bank to underwrite the loan.When I purchased from a private auction, after winning a normal purchase contract was executed indicating all of the terms.