have a look on the christmas bargain threads - lots of ideas.
ebay.com is also your friend - lots of stuff that comes from china etc is priced at (say) 99p on ebay.co.uk but 99 cents on ebay.com - so with the difference in exchange rates it means it's about 65-70p instead. Do searches on ebay.com and order them as lowest price + postage first to see the good bargains.
There are often things that have an auction going on that they start at a cent with free postage (how they make money I don't know!) although they rise more than that usually, so you can get some ridiculous bargains. But if you need things more speedily then just use the 'buy it now' option to see stuff and buy it with no hanging around.
You can use your ebay.co.uk log in and paypal so it takes care of any foreign currency exchange.
Depends on how much time you have until it's needed... Can sometimes take three or four weeks to arrive although some stuff is much faster.
Things I've bought on there as stocking fillers / presents/ bits and bobs include:
reusable shopping bags - which compress down to be roses, strawberries, clown fish, and more, buy it now price starting from about 75 cents (50p) - good this year now we have to buy plastic bags
kawaii stationery - especially post it notes and memo blocks. Have had some bargains on these. Usually very cute stuff, lots of stuff around a dollar.
Little silicone sucker stands for iphones/ipads - single ones for 99cents but also managed to get 5 packs for a couple of dollars. Shapes include little men (my favourite), pigs, robots, balls. There are also other little stands like elephants - I saw them for sale recently in the UK for £5 in somewhere like Paperchase and got them for less than a dollar.
Other silicon stuff - little snails that sit on the side of your cup to hold onto tea bags, cup covers, cord winders for headphone cables (come in all sorts of designs if you know somebody is into something in particular),
Bag organisers, little make up bags, pouches for cables, pencil cases etc.
Scarves - can be ridiculously cheap, especially if you can be bothered to look on the auction stuff - order by finishing soonest and you might see stuff you like that nobody else/very few others have bid on
Santa stuff - slap bands (probably a bit young but if going for the silly stuff or bags to put a bottle or two in)
TEmporary tattoos or the nylon fake tattoo sleeves - can be very cheap
However...
I'd avoid anything to do with food or makeup or stuff where their lower standards might have a detrimental effect, despite seeming cheaper they might be a false economy!