Hi Suzie
If I was looking for a good kitchen knife there are a couple of things I would look for:
Where the blade meets the handle it should become thicker, probably with an oval section piece. The handle then fits onto this fatter bit. The reason is that any sideways force on the blade produces the largest stress in the metal where the blade meets the handle and this thicker part is strong enough not to bend or break.
Also look to see that the handle (usually two pieces of wood or plastic) are properly riveted onto the metal. It can be hard to tell but look anyway.
You can get knives with stiff strong blades which are good for most jobs but it is also useful to have a small knife with a flexible blade. These cost quite a lot but the strength and springy nature of the blade means that it is tough and won't break.
If you buy a well made general purpose knife, the blade with probably be made of good quality stainless steel. These are tough, do not rust and take a good cutting edge. However, the steel can't be very hard or the blade edge gets chipped like it was made of glass. Cheap stainless knives are quite soft and any edge quickly wears away and they go blunt. However, you can also get Japanese knives with a very hard edge and these are great for finely slicing meat BUT the edge is easily damaged. These are expensive.
If you can get a diamond sharpening 'stone' (it is really a piece of metal with fine pieces of diamond pressed into the surface) it is really good at producing a fine sharp edge on any knife. It is not meant for grinding metal but just producing the final cutting edge so it is to be used carefully. An oil stone is better if the knife needs a new edge, then use the diamond stone for the last few strokes.
Now as to price. I think the best knives come from Germany - probably Solingen. A small knife will be around £20 and a large one (for carving the Sunday roast) £25 to £30. The Japanese carving/slicing knives cost £45+.
Now these knives will last you all your life if looked after. They will stay sharp, cut through tough stuff like pig cheeks and sinew like it was butter. The handle won't come off or apart and they will be a pleasure to use.
Look in a good kitchen shop locally or if you can get to London or other large city, go where the restaurant trade get their equipment. In London this is just south of Soho where Charing Cross Road meets Shaftesbury Avenue.
If you are offered old fashioned non-stainless steel knives, they can be very good but they do rust and therefore need drying after washing. The edge rusts and this blunts the blade. They aren't good for cutting fruit as they rust and spoil the taste of the fruit as a result. You can't put a decent knife in the dish washer either.
These links might help
http://www.knives-from-solingen.com/ha.htmhttp://www.japaneseknifecompany.com/JKCSHOP.aspx