What can I do about a Paper Wasp infestation cheaply?

Paper wasps don't make nests within structures, that could be hornets or bees. The paper wasps will more likely hide nests under eves and overhangs, but you no doubt have ways they can come indoors and nests near them.

Locate entry points and seal those off. Strays that enter can be returned outside, a saucer with some crushed fruit like ripe grape or berris works, as does honey or jelly, The wasps go for the sweets then kindly escort them outside. I have even done that by hand and not stung. I had an issue with them migrating through the area a couple years ago, 2 dozen nests under the eves and window sashes, over a thousand individuals. At least they are not much for aggression, and being pollen eaters are a good bug like bees. I try not to kill them. and just dealt with their presence, and hardly any the next season. If you feel you must rid them my choice is to call a local apiest or exterminator with bee/wasp experience to relocate the wasps. Killing them should be last resort. 6 indoors is a good number to suggest this is likely beyond your control unless you are willing to ride them out. working outdoors near the nests, just refrain from bright colored clothing and avoid sweet smelling soaps, colognes, and perfums and they won't be attracted to you, Don't threaten them or their nest and they leave you alone. I found them fascinating being new for me and did a little study. I have kept bees so a moot point for me. Here, I attracted a few to eat a crushed grape from my hand, and never stung doing this:

https://www.flickr.com/photos/32083154@N02/9767704...

The cheapest is learning to live in harmony with them around, next would be consulting an apiest/bee keeper to evaluate what can be done. Bringing in the pros may not be all that cheap, but usually effective.

If you simply must kill them, I suggest raid yard guard. Locate what nests you can during the day, then return after sundown when they will all be on the nest and spray each nest, hopefully getting the queen. For your number guesstimate, you could have quite a number of nests nearby, likely more starting.

Seal up their entrance, even with duct tape if necessary.

Your methods won't work. You need to solve it permanently - use a service, don't be so goddamned cheap.

A product to use is "Jet bee Bomb." It is pure ether. You should be able to get it from your local nursery. Use it after sundown. All the wasps will be in the nest. Cover the entrance with tape. They go peacefully to sleep and don't wake up.