The least expensive type of fencing can vary depending on various factors, including the materials used, the size of the area to be fenced, and the region in which you live. Some of the most budget-friendly fencing options typically include:

1. Chain-Link Fencing: Chain-link fencing is often one of the most cost-effective options. It consists of metal posts and a mesh of interlocking metal links. Chain-link fencing is durable and requires minimal maintenance. While it may not provide as much privacy as other types of fencing, it is excellent for security, defining property boundaries, and keeping pets in or out.
2. Barbed Wire Fencing: Barbed wire fencing is primarily used for agricultural and livestock applications. It is a simple and cost-effective way to keep animals confined to a specific area. However, it is not suitable for residential or urban settings.
3. Split Rail Fencing: Split rail fencing is a rustic and economical choice. It consists of wooden posts and horizontal rails and is often used for decorative purposes or to define property boundaries in rural areas. While it doesn’t provide privacy, it can give a charming, country-style look.
4. Wire Fencing: Wire fencing, such as welded wire or livestock wire, is another affordable option used mainly in agricultural and livestock settings. It is suitable for containing animals and defining boundaries.
5. PVC or Vinyl Fencing: PVC or vinyl fencing can be budget-friendly, especially if you choose a basic style. While higher-end vinyl fencing options can be more expensive, simpler designs can offer cost savings. PVC fencing is low maintenance and durable.
6. Wood Picket Fencing: Traditional wood picket fencing can be relatively affordable, especially if you opt for pressure-treated pine or other budget-friendly wood species. Wood picket fences are known for their classic appearance and are often used for decorative purposes and front yards.
7. Bamboo Fencing: Bamboo fencing is a low-cost option with an attractive and natural appearance. It is often used in garden and decorative settings. While it may not provide significant security or privacy, it can enhance the aesthetics of outdoor spaces.

Keep in mind that the actual cost of any fencing project can vary based on factors such as the length of the fence, labor costs, additional features (e.g., gates), and the specific materials chosen. Best to obtain quotes from local contractors or suppliers to get a more accurate estimate for your specific needs and location. Additionally, consider the long-term costs, including maintenance and repairs, when choosing the most budget-friendly fencing option for your situation.