Yeast from my last brew

I am on a very tight budget these days so I have been trying to homebrew enough that I don't have to buy beer anymore. I already have plenty of grain and hops but money is especially tight this month so I would like to avoid buying fresh yeast this time and reuse some from my last brew. I have plenty of bottles which have not been refrigerated since bottle conditioning, I was wondering if I could pour half of a bottle or maybe half of two bottles into a glass so I'm not wasting beer and then twirl the remaining beer at the bottom of the bottle to make a slurry and put that into the chilled wort in the fermenter?

If that isn't a good idea what about pouring most of the beer out of the bottle and replacing it with a boiled (and cooled) corn sugar solution and putting an air lock on the bottle and wait until I have it actively fermenting before I brew and pitch that?

You will end up spending more money on the DME needed to make a yeast starter from that little bit of yeast that you have. Maybe not more... but you will need to spend money. Probably need 4-5oz for the first step... then 6-9oz for the second step. Youll basically get a point of DME for $5.

Go grab some nottingham. Its generally under $2 and its a great neutral yeast.

Then, plan ahead for the next batch to either pitch onto the yeast cake OR harvest. Plenty of threads on both of these topics right here !

You will need to step it up. The cost of DME in the grand scheme of things is negligible compared to buying more yeast. And cheaper than buying more yeast, even dry. Of course, if you brew AG and buy in bulk it is even more so. As you can just either use the last runnings and can, or brew up a weak wort and can for starters. Or forgo that link and go to the other one that is stickied, and slant the yeast. Then you'll never run out.