the one I used costs $4 (with shipping)
Could you please clarify, why is your reply relevant to my cheap project?
Silicon Labs, Austin, TX (USA) is one http://www.silabs.com/products/interface/usbtouart/Pages/default.aspx
of 2 well support and widely available USB to UART (TTL) or Serial (RS-232) chip manufacturers,
the other being FTDI, based in UK.http://www.ftdichip.com/FTProducts.htm
Prolific USB chipsets (Taiwan) found in many inexpensive "big box" store bins ---
suffer from poorly support for COM/VCP drivers for various Operating Systems (OS).
In fact, the Prolific web site has been unavailable in recent weeks.