You need to preserve some liquidity so you shouldn't inject every penny you have.Perhaps the owner would be open to a staggered payment of 25K for 3 years?

Glass can come with a low E coating or not.

Check any low priced or free classified ads like penny saver or what is local to you.

First major step is to get the best paying job you can find, two if necessary, live frugally and save every penny you can.

Screening will save you many a headache financially and literally if you trying save pennies and lose dollars.

@Penny Clark  your points are very valid and not something that I had thought of, especially the 6 month cushion but it makes sense just in case. 

Should every penny of the 7k for each year be held in an account until it is needed? 

This is not a traditional deal, if circumstances were different I would walk away from this house, but my parents are stuck with it and I want to help them sell it and not have it cost me a penny at worst.

just a couple pennies to consider...

There's been  a lot of discussion here on BP about whether or not conferences are worth what you pay and I have to say the Paper Source Conference was absolutely worth every penny.