Bamboo are infrequently grown from seeds since they hardly ever flower. That's why you're not finding packets of them next to the carrot seeds at your local nursery. You're limited to getting seeds of the couple of bamboo that are flowering now. There are some F. nitida seeds around, some Ph. heteroclada, and some moso. There are also a couple more varieties I've seen available on eBay, but mostly they're from outside the U.S., and are technically illegal to import. If you find seeds, there's always the question about how fresh they are, as they lose viability quickly. There are a number of threads in this forum on growing from seeds that will give you an idea about how easy/hard it is to grow from seed. I've done it for the fun of it, but it's a slow way to get plants of any size. If you're able to grow them this way, they might reach 3-4' in a couple of years. That's why most of us buy our plants as divisions.

I've been growing moso in Zone 8 that I started from seed about 5 years ago and it is about 5'-6' tall and -- while it is a runner -- it still occupies about an 18" circle. It may grow faster for you in your Zone, but it would take many years to cover an acre, if it ever did. You may have heard too many urban legends about running bamboo... Oh, and by the way, if you're buying seeds on eBay from non-U.S. buyers, you're violating U.S. import regulations, which require a one year quarantine on bamboo plants and seeds. Often, it slips by. However, if the USDA gets wind of this, you may get a visit from a federal agriculture inspector. If you think I'm blowing smoke, I know two people who had this happen to them.

Your seedling will not have continuous growth, and will stop after several months when it is several inches high. Each successive year it will put up new shoots that be somewhat bigger. In 3-5 years it may be about chest high. I started moso from seed 12 years ago and it is probably 15' tall in my temperate, Zone 8 climate. If you want to repot it, you can, but don't disturb the roots: try to get the soil ball out of the container intact using a spoon or small trowel.

Growing from rhizome is often only marginally better than growing from seed. What you need to do is buy an actual division if you want to see it attain any significant height in the next 5 years. There is a reason that bamboo plants can seem pricey, and it has to do with how much time the grower has to invest to have a salable plant.