As online shopping gets more popular, companies that specialise in shipping are emerging. These companies have 2 attractions:
buy from shops that don't deliver overseas
They usually work by giving you their overseas address. You have your shopping delivered to them, and they ship it to you. 2 companies that I know of are Vpost and I just heard of Hopshopgo. I'm comparing prices with Monoprice's own delivery, since I just bought something from them.
Monprice: order cost $45.35, weight 3.31 lbs, shipping $41.54
Hopshopgo: $26.72, which is a lot cheaper. Not sure how fast their shipping is, but it'll probably take longer than direct from Monoprice.
Vpost: SGD$39.24 = USD$31.37. Looks like Hopshopgo is the cheapest.