An A-Z of the ingredients I mention in the recipes and which you're likely to find most useful:

Coriander
An addictive fresh herb, commonly used in Indian, Mexican, middle-eastern and North African cooking (also known as cilantro) The dried seeds and ground powder are used in these cuisines too.

Curry paste
A much cheaper way of making curries than buying a cook in sauce. You only need a spoonful or two - a jar should last most of a term if you keep it in the fridge. Patak's are a good make.

Eggs
Even if you're on a budget you should try to buy free-range eggs for humanity's sake. Medium eggs are usually better priced than large ones.

Garlic
Worth buying fresh unless you hate the smell/mess. In which case buy a ready-made wet garlic or garlic and ginger paste. A clove btw is one section of a garlic bulb, not the whole head!

Grana Padano
A slightly cheaper Parmesan-style cheese that really makes a difference to pasta dishes. Cheapest (and best) from Italian delis.

Lemon juice
Freshly squeezed lemon juice tastes best but bottles of lemon juice are cheaper and keep better.

Marigold Vegetable Bouillon Powder
My must-have ingredient. Far better (more natural-tasting, less salty) than stock-cubes and you can measure out exactly what you need.

Marmite
Even if you're a Marmite-loather you'll find it comes in really handy for stews and gravies.

Moroccan Spice Mix
A home-made spice blend that I find invaluable for seasoning all kinds of dishes. Mix 2 tbsp each of ground coriander and cumin with 1 tbsp turmeric and 1-2 tsp chilli powder, depending how hot you like your food and keep in a jam jar or airtight tin or plastic box. Use to taste - about 2-3 tsp at a time

Mustard
Useful for making French-style salad dressings and adding flavour to sandwiches. French Dijon mustard is by far the best - buy it in bulk if you're in France or know anyone who's going on holiday there. It's far, far cheaper.

OIl
It might sound extravagant but it makes sense to have two kinds - a cheap oil for cooking (vegetable or sunflower) and a better quality extra virgin olive oil for making salad dressings or drizzling over food. Look out for special offers on the latter.

Parmesan
See Grana Padano

Pasta
Authentic Italian pasta tastes better and has a much better texture than cheap supermarket pasta and worth buying if you can afford it

Rice
Nutritionists will disagree on the basis that brown rice is better for you but nothing beats the flavour and texture of basmatti.

Soy sauce
I find light soy sauce the most versatile. If you've got a Chinese or other oriental supermarket nearby, buy it there in large bottles. It's a great deal cheaper.

Stock cubes
I'm not a big fan - most are too salty and taste unpleasantly chemical. I prefer Marigold Vegetable Bouillon Powder or at least use organic cubes.

Tomatoes (tinned)
Better - and better value - than fresh tomatoes in most pasta sauces. Buy them whole rather than chopped

Tomato paste
A good way of getting intense tomato flavour into a dish, especially if you're using fresh tomatoes. Buy it in a tube rather than a tin - it'll keep better

Vinegar
Essential ingredient to make salad dressings and sharpen up other dishes like pasta sauces and stews. White or red wine or cider vinegar are the most versatile.