Hi Becky,
The charge of around 54p to send a postcard to the US from the UK sounds about right. Remember, the 32p charge is for UK to UK delivery, so 22p or so more to get it to the USA seems correct.
Now for some lateral thinking...
Gather up all 15 of your postcards, and send them together to your home/family address. Then get a member of yer family to send them out domestically within the US. I'd hazzard a guess that by sending them this way, it'll overall cost less than 15 x £0.54 = £8.10.
slight guess, 15 postcards would cost about £2 to send as a package to send from here, seeing as it's so light. Then if the domestic post charge for each is about 40c which is 20p then that's about £3. So the total is around £5.10 equating to around a 40% saving!
Stick another pound in and nip over to tesco and pickup 5 'long term price deal' frozen meals for 4 quid!
Also as a student, you need to work out more 'inventive ways' of making money to help you along - I have *cough* suggestions which I used to do at uni, but not sure if you'd do those - maybe just the 'less bad' ones!!
hope that helps!
Cheers! DtM! West London & Slough UK!