If you are looking to "hold out" making your platform decision until you have Zambezi (consumer version of bulldozer) data then you are looking at 9-12 months realistically.
For purchases a year from now you'd be better off finding a high interest-rate bank CD and just putting your money to work for you until you need it.
Computer parts rarely increase in price, and when they do it tends to be more of a temporarily thing that quickly subsides in a matter of months anyways.
I would not buy a hard-drive today if I wasn't going to use in until next month let alone if I actually wasn't likely to use it for a year.
Same with computer cases. Anything that is made overseas and shipped here is highly subject to currency fluctuations. (my current job is foreign currency trade) In the coming 12 months there are very few things that are going to depreciate in value faster than your cash itself, and one of those things is your computer gear.
That's not to say don't take this time to seek out those truly awesome clearance opportunities and open-box situations. You can come out ahead in those cases, but never ever with retail pricing.
edit: just noticed the OP is UK...the sterling is a different story than the USD for next 12 months. Your sterling is going to appreciate, not depreciate, in coming 12 months so even more reason to keep the cash as cash in a bank account until you actually go to spend it. The exchange rates will favor your purchases in the future with computer parts being even cheaper owing to a stronger pound in the future versus now. (and the NFA requires me to add the following to this post now that I've gone and said the above)
These opinions can be a valuable addition to the investment or hedging goals of our readers. Investors are reminded of the inherent risks associated with trading in the foreign currency exchange markets, much like any leveraged investment vehicle. This is not a solicitation or recommendation of any order to buy or sell, but merely a current market bulletin. Any statement of facts herein contained are derived from sources believed to be reliable but are not guaranteed as to accuracy, nor do they purport to be complete. No responsibility is assumed with respect to any such statement or with respect to any expression of opinion herein.