If you purchase the new ones that are just under 6' tall - those were the best value ones to get if I recall correctly.
The price of poker went up about 35% for the ones just over 6 feet tall.
If you have over 20 holes to dig ... I would sub out the hole digging to a couple hungry / cheap teen agers. I dug all my holes by hand myself at around 50yo and nearly gave myself a heart attack ( hahaha ) Or if you have a friend with a tractor and auger.
They grow pretty face if you fertilize and water them during droughts the 1st few years. After 3-4 years are zero maintenance.
5"-6' right off the bat would be a great starting size. Being the maximum value size is a bonus!
I live in an agricultural area- everyone has a tractor and I know a few are sure to have auger attachments. I'm not doing the fence thing at this point, just a few for accent/fill-in.
As for the fence thing, I'm purposefully being "that guy" with visible project vehicles and questionable yard activities in hopes that my new neighbors will build a fence. We're all neighborly and friendly, but his house and shop was recently completed so he's still in "build mode". He's setting up his patio area for entertaining so I'm sure he doesn't want his eyesore neighbor to be visible to his guests. He's mentioned needing a fence to "keep his dog in"... the dog that seems to love me a lot more than him.