I had a quick look on Aliexpress and they have hot knives for $15 - $22, they seem to be 2mm dia and various lengths, up to 100mm. (for cutting styrofoam)

My experience of goods from China is that they are slow to arrive, Aliexpress is slower than eBay. American goods are always saddled with customs charges and handling fees, which generally pisses me off, especially when you can't always find out the total cost in advance.