I think bamboo is expensive because it is a specialty item and takes a while to propagate. Seeds are hard to come by because bamboo may take decades to mature and make seed. The nurseries also usually don't grow the 'common' varieties, even across the clumping types. They grow the more unusual types with special colors or forms for collectors. On my property I have a timber type and offered it for free to the bamboo nursery across the road. They didn't want it because it was 'too common'.
That is a lot of ground to cover. You might need 100-200 plants. Choose carefully based on viewing an established clump. Learn tp identify running vs clumping. Probably you should look for the generic 'Multiplex' bamboo if color or form isn't important. You might consider searching for someone NOT in the nursery business who has an established planting they need to thin/restrict. Offer them some money. Digging bamboo is a tough job, especially in clay/rocky soil. Some varieties you can propagate by rooting side branches. That will take some time because the first shoots will be thin juvenile reedy canes. Over several seasons (years) those will increase in size to attain the final adult diameter. From that point, the plant will begin sending up adult size shoots. That may take 2-3 or more years.
Planting established full diameter rhizomes instead of cuttings will yield larger culms faster. If you can't get enough stock at first you could plant at wide spacing and backfill a trench around the inner and outer sides of the planting with mulch. As the clump grows it will send rhizomes into the mulch which will be easier to harvest and replant between the existing clumps. Do not harvest rhizomes along your screen line so that it will begin to close up.
good luck.
I am covering 350 feet and have propagated 50 plants from branch cuttings, so one every 7 feet. My intent is a windbreak, a screen and harvesting edible shoots so I have chosen an edible shoot timber type 30' mature height. I got the cuttings free. Will use irrigation, mulch and a temporary screening plant down either side called Tithonia Diversifolia. It does not reseed, grows easily from stem cuttings to 10 feet in one rainy season. I will prune each side of the tithonia alternately to maintain a screen and the prunings will provide renewed mulch for the bamboo in a sustainable manner.
Eventually, the tithonia can be removed or allowed to decline as bamboo takes over.
Description ( w/a little exaggeration):
https://www.youtube.com/watch?v=wYFj_7lBAPM