Everyone is restrained by a budget of some kind. When you begin planning your home office, you won't be the only one restrained by a budget. Having a budget to create your office is great practice for budgeting other areas of your life. You can still have a great office -- even with a shoestring budget.
You do not need to buy new furniture for your office. You can find plenty of stores that sell used furniture and you can often find furniture with bargain prices. What about an old-fashioned desk for your computer instead of one made especially for the job? You'll get heaps more room and you'll probably be able to fit a set of drawers underneath it.
If you haven't bought a computer yet, think about getting a laptop instead of one with a monitor. Why? You can save heaps of space by using the laptop on the slide-out keyboard drawer of a computer desk. Then you'll have free space on top of the desk for other activities as well as space on the wall behind for a small corkboard or even a hutch. You can store essential paperwork on that or anything else that you need to reach easily and often.
The space that would have held the CPU can store many other things. Measure it carefully and see if you can get stackable, slide-out storage for it. And thinking of computers and all the other electronics you'll need, keep a watch out for sales and discounts that will save you a bundle. Even buying online can save a great deal.
Browse thrift stores to access pre-loved furniture and other accessories. Garage sales, eBay and other auction sites, both online and offline, are good places to find bargains. You can easily find discount office supplies from advertising.
Unless you need to finish your office in a hurry, don't try to do it all in one day. If you start with the basics and expand gradually, you can still work from the office while you wait to find the extra pieces you need. This is a good idea if you've never worked in an office before and are not sure how it should all fit together or what else you need.
If you have a choice, choose the store that offers free delivery, otherwise see if you can handle the delivery yourself. This could save the costs of store delivery that costs $75 or more.
If your home office must share a room with others in the family, you can find other ways to make it a private space -- or at least define your work area that encourages the rest of the family not to intrude.
To start, you can gather all your office equipment into the one area. Don't spread yourself around the whole room with your filing cabinet on one wall, your desk along the other, and the bin in a corner near the doorway. Instead, keep everything along one wall or in the corner. One exception would be if you have a filing cabinet of records or things you don't need to access every day. You could free up some extra office space by locating this in another room.
You may be able to use the back of the sofa as a low wall to define your workspace -- but don't be surprised if your kids climb it to reach you. A bookcase against the back of it may stop this problem and give you needed storage space. Or you may find it enough to mark off your office boundary with a low coffee table or a couple of indoor plants.
Storage units are probably the most effective way of defining your workspace, as they will do provide storage. If you want to keep an eye on the kids, then you need to keep the storage below your eye level when sitting. The height of a three-drawer filing cabinet is about right. If you have taller storage, you could have one on each side of the desk area (but behind you) so you can view most of the room from your chair.
Try and keep your workspace out of a walkway. If people have to go through your workspace to access other areas of the same room, then it is in the wrong place. They may also need to go through your space to access other rooms. Try to avoid this, if possible, or you'll never get any peace. Start off by re-designing the layout of the furniture in the room, even if you need to change the electrical outlet positions. Draw up a plan to scale, or measure the new positions and the furniture to make sure it will fit.
If your children are at the crawling stage and into everything, it might be prudent to install low fencing around your workspace to keep them out. This often works better than confining them in a playpen, as they have more space to explore and are less likely to cry for attention.