As far as walking equipment is concerned you should always by the best you can afford, that doesn't necessarily mean the most expensive. If money is tight then there is an order I feel that should be prioritised:
Boots and socks - your feet are your most important assets you'll need them to get home, make sure your boots are comfortable and fit well Cotswold Outdoor offer good advice on boot fitting. Socks are important too you need to ensure you feet are neither to hot nor to cold, I like Bridgedale socks and have several pairs of different thickness'.
Core - keeping your core warm is vital, so make sure that you have good layers so you can maintain a comfortable temperature. I start with a wicking base layer and then layer fleece and a shell on top. Fleeces and Shell I tend towards The North Face, I have a selection of fleeces both micro and windwall, to allow for difference temperature conditions.
Head - always keep a hat in your rucksack as no one likes having a cold head.
