I was just typing up a reply but Necro beat me to it and said pretty much exactly what I was gonna say.
The $ you save on a CD combo over a Duo would probably be negated by the cost of the more expensive Arcade Pro card.
I'd definitely check out the Duo-R and RX (and I'm not just saying that because I have one, LOL). They seem to go cheaper on the 'bay than the US Duos (even including the overseas shipping sometimes). And the Duo-R and RX did not have many of the capacitor issues that the original Duos had (which might not be an issue if you're handy with a soldering iron).
I paid just over $200 shipped for a perfectly-functioning Duo-R, two pads, a tap, and an Arcade Card Duo. I bought a separate base TG16 unit strictly for US HuCard duties, but the Duo-R is being region-modded soon so I can sell off the TG16 and have one console to play everything.