It's true monoprice isn't always the cheapest, but they're a known entity, unlike some random hong kong seller on ebay. That being said, $5 with free shipping is a pretty good deal on an HDMI cable, since you'd likely pay about $4 or so on monoprice with shipping.
9 times out of 10, they all get them for 5cents from China, then sell them for a dollar or two or a 1,000(lmao). That monoprice place charges over $2 for shipping and, if they are in the US, they should just charge $2+ for the cables and the 99cents or less it, actually, costs them to ship the item.
When I order HDMI/s on eBay, I order from US sellers. Got a 9' Insignia(I think it's Best Buy's brand) brand new for $4.99FS, a while back.