While I'm a pro in software engineering, and most things about the hardware, I must admit the people here are much "deeper" into the DVD drives than I (one can't know everything ).
Following advice from various threads here, I picked up the NU DW163 from Newegg for about $60 delivered (black bezel, they want quite a bit more for the beige). It's a genuine BenQ 1620 - flashes to "Pro" level 4x dual layer if you want.
So far I'm amazed (had the drive about 10 or so days now). It shipped with "G7H9" firmware, and I opted to stay in "G" firmware, moving up to G7P9, which I'm happy with.
From the same vendor I opted for a cheap stack of +R 4x Optodisc (50) for about 26 cents each, which consistently give me scans of 97% quality, and play without problems in all the stand alone players I've tried (including a very picky, ancient Yamaha).
My next pack of media will probably be Ritek (RiData). Right now a 100 pack, including a rebate, of 8x RiData can be had for under 40 cents a disc, delivered. There's a section here on "deals" - but as I've looked around and read here one must take care. The brand and the manufacturer may have little correlation, with few exceptions. These slow Optodiscs of mine are ok, but I've read much greater satisfaction from RiData. Check the very long thread of scans ("post your BenQ media here") and you'll get a feel for variations in media types and quality.
Take note about the rebadge packaging, though. The NU DW163 doesn't come with a cable, and you should use an 80 wire type - not the older 40 wire type.