Thoughts on 2.0 vs 4.0?
2.0 is by far the most used version; 4.0 is not necessary for your application (low data rate devices, especially sensors). 3.0 has a HS/Hi-speed mode, which could be useful for music fidelity.
Looks like the ebay options bump the price to ~$5 for the 3.0/4.0 models (looks like if you go for something higher than 2.0, then may as well go for 4.0).
For another $1 or $2 you can then add USB 3.0 - the higher speed version of the USB interface... that is, if your laptop supports it. If made within the past ~18 months or so, then it is possible. If not, then it’s most likely a USB 2.0 interface, but either way, it’s not a big deal.