Using a Wireless-N WiFi Repeater vs turning an old router as repeater

Based on an article on the 'Lifehacker' website I noticed an article on how to use an old router as a repeater. I was looking at eBay and noticed something called, "Wireless-N WiFi Repeater Router Signal Range Extender Amplifier 300Mbps" which appears very small, and is just inserted in your USB port of your laptop.
This begged the question: At US$ 13 with shipping included perhaps it is better to buy this as opposed to converting my old ''D-link DIR-300" in a repeater, especially if doing so is a real hassle.
Hence trusting you guys here I thought I'd ask you if you think there are advantages and disadvantages with one or the other.
For ex. a disdvantage to using my old router as a repeater is that it's not portable
an advantage (sort of) is it's free
the eBay one at this price range seems to have 2 different models of brands unknown to me--China
-1- VOnets and -2- LB-Liink (seems to be imitating the 'D-Link' logo)
[This 2nd 1 seems to come in 2 slightly different definitions 'USB Wifi Router AP Wireless N repeater Adapter WLAN Range Extender F' or 'USB Wireless WLAN WiFi Router AP Client Repeater Adapter SY']
You opinion is valued. Thanks

Wow 129 people viewed this but no one had an answer. Could this mean other people are possibly interested by having the same question; thus they too are looking for an answer?