Today there are so many options to choose from that it is not as simple a question as it first appears. Are you looking for the most inexpensive option or would you like it to be a higher quality, more decorative product that will add to your homes curb appeal? A better question might be how much do you want to spend or what do you want the final product to look like?
There are very simple configurations that can be purchased from any major home and garden store, a wooden pressure treated, or simple steel post and a basic galvanized steel mailbox are probably the most common, followed by a variety of vinyl products that are typically meant to slide over a secure inground post or metal stake. There are also many different manufacturer sites online that offer several upscale, more decorative products that also can include many options like personalized address and street plates, fancy brackets, finials (those little decorative tops for a post), newspaper holders and plant hangers. Installation is the other significant expense when pricing out a mailbox installation. Key factors will include removal of the existing mailbox and construction materials, purchase of supplies like concrete, a mounting plate, house numbers, etc., and in some cases the assembly process can be more involved.
If a homeowner has purchased a mailbox ($25-$200) and will be assembling all the mailbox components and installing the post and mailbox as a DIY project, additional costs may be in the $50 to $100 range depending on the type of post and materials required. Most handyman services will usually charge $150-$250 just for installation depending on the complexity and the homeowner requirements for post material. If the mailbox installation service provides a mailbox, post and install, costs will include the manufacturer, type of mailbox and post system selected plus the installation. Prices for higher quality mailboxes and post systems can range from $200 to more than $800 based on the type of mailbox selected and quality of materials.