Hiya
I often export products from the UK to the US (and vice versa!) and I'd suggest taking a look at the discount courier companies as well. The UK pricing for sending parcels and packages has more competition, so prices are relatively cheap for sending stuff.
here's the links
http://www.parcel2go.com/http://www.p4d.co.uk/There's probably a few others, but those are the two main ones I use. Royal Mail I tend to check for smaller items which it sounds like you have in this case, but as always, no harm in shopping around!
With the couriers I also like the fact I get a tracking number, a pickup from my house, and in some cases when I've gone for the economy 5 day service, customers have informed me it's arrived on the 3rd day!
Hope this helps!
Cheers, DtM! West London & Slough UK!