People often ask me what they can buy a camera crazy person in their life that wont cost the earth :-)
There are lots of smaller gifts you can buy that will be of great value to a photographer and that only cost a few pounds.
If they don't have a tripod and want to start trying night photography, you can get a reasonable tripod from Ebay or amazon or the like for not a huge amount of money, they start at just £7.95, but I've seen some on there for around £23 and they look quite a bit more substantial and would make a great gift for the photographer in your life.
Next on the list would have to be some really much cheaper products - things such as lens cloths, having a few of these handy is always great, plus a really sneaky gift that will impress the photographer in your life is a UV filter for their lenses. If you have a look at their DSLR when they're not around, have a look to see if they have a UV filter, these come in handy for several reasons, but the main one is, having one of these screwed onto the front of your lens means if you knock your lens against anything it is the filter that gets scratched and not their lens. To make sure you get the right size filter for their camera- take their lens cap off the camera and you will see a size in mm - it might say anything really - 49mm, 52mm, 67mm but then you can buy the correct size filter for their lens :-) you can also buy these on Ebay and Amazon and all good photo shops at a variety of prices, but they start from around £5.00.
You could also check to see if they have a polarizer filter too :-) you can buy these online too, once again check the filter size on the front of the lens you want to buy it for and they start at the same price as UV filters.
There is of course also my new book - 12 months of Photography Ideas and Projects that you can find in my shop for just £10.
If you want to spend a little more money on them, I sell vouchers for one to one training from £95 for a half day.
I hope whatever you decide to buy for them they enjoy using, I'm sure they will :-) maybe a subscription to their favourite photography magazine would go down well too ?