USA Customs charges?

I'm making my own invites. Saw some fabulous metallic paper but shop doesn't have enough of it and can't order any more for me. I can order it online but only from the USA. I'm worried that there will be hidden charges though when paper arrives at my end like customs charges, vat, etc. Has anybody ordered any good from USA or does anybody know anything about this?

Depends on how much the paper costs. there's a minimum below which there's no need to pay VAT.

Only about $25 - do you know the limit?

Will be fine. I can't remember what exactly it is, (might be $40) but it's deffo under $25!