When purchasing end tables, the first thing to consider is how they will feel in your space. Do you really like the look, the feel, the style? If not, keep looking. Even if you are on a strict budget, there is no sense buying furniture that you do not really like just to save money. You will end up spending more in the long term, because you will have to replace your end tables sooner.
You can find great tables at reasonable prices if you shop around, but don't restrict yourself to pieces that are intended for use as end tables. Do not overlook items that are usually used for other purposes. For example, nightstands make great end tables and often have convenient drawers or lower shelves for storage.
Wicker cubes with lids make terrific, inexpensive end tables as well. They offer a great way to add some texture, and they are an especially good choice for small spaces because they not only work as tables, but also offer extra storage. In a pinch, they can even be used for extra seating.
If you are looking for more conventional end tables, the most important thing to keep in mind is scale. If end tables are not the appropriate size and construction to compliment existing furnishings, they will look out of place. In other words, you don't want to use tiny, delicate end tables next to large, chunky sofas or chairs. A more substantial table would be more appropriate. At the same time, bulky tables don't fit well with slim, slender chairs either.
If you find end tables that you like, but that don't exactly match your space or the style of your other furniture, you may still be able to make them work. Common elements help unite pieces that otherwise would not go together. If your sofa and coffee table are fairly contemporary, but you find gorgeous antique end tables, you can still use them if they are the proper scale. Also, consider painting the end tables in a similar tone to the rest of your furnishings to help them blend in better.
Be sensible when buying end tables and try to avoid being tempted by items that are outside your budget or impractical.