Regarding the price for landscaping for privacy when compared to a fence, my guess is that landscaping would cost about $20-$50 per plant and you would need 1 plant every 4-6 feet depending upon what you choose. If your yard is 100 feet by 60 feet, you would need about 30 - 40 plants for a total cost of about $600 - $2000 plus labor.

If you buy plants and do the work, it will be even cheaper. If you start your own plants, even cheaper yet. It can become practically free!

Don't expect much in the way of sound reduction out of a row or two of plants. It takes more like an acre of planting of the right thing to get reduced sound. But you can certainly screen what's outside of the fence and that will help minimize awareness of it. A solid masonry wall will provide the best sound reduction. Other materials will help, but be less good.

If you just want a straight, simple hedge, there's not much to it other than selecting what does that and grows well in your area. What are people there using for hedges? Decide ahead of time if you wish to have something that grows naturally, or if you want to keep it trimmed (which can be a fair task, depending on its height.)