If possible always purchase easily damaged components, or components that are difficult or expensive to return, such as hard disk drives and monitors, from local stores.
When you purchase a new computer, you should certainly make sure that it is as upgradable as possible, that it is good value for money in that it does not contain any 'ancient' components, but you can certainly take your time when purchasing upgrades.
The latest hardware, such a processors and video cards, etc., are usually extremely expensive compared to the price they will be after they have been available for some time, or have been superseded by newer models. By keeping a few paces behind having the latest equipment, you can save yourself a small fortune while still having a machine that can run the latest software perfectly adequately.
Note that if you're waiting for the price of a particular processor to come down before you make a purchase, be aware that there comes a time when processors very suddenly become unavailable. The manufacturer no longer makes them and supplies have run out, but the suppliers are still advertising them because they have to submit their advertisements to computer magazines long in advance.
Therefore, don't rely on advertisements to judge the availability of a processor. You'll eventually be able to obtain one second-hand or from an obscure source, but not without going to a great deal of bother and an increased risk of being taken for a ride by con-artists.
