If you plan to buy Wind Waker, consider that you won't just be able to buy just the game itself. You also need a gamecube controller and a gamecube memory card. By the time I bought mine I think it added up around this amount (US dollars):
- Wind Waker ($20 used at Gamestop)
- Controller (~$15)
- Memory card ($15 from Amazon.com, though half of it was shipping)
It was still a worthwhile buy for me because you can get lots of used Gamecube games. I got Animal Crossing for $10, for example...a couple Marios for $10 - 15...Soul Calibur II and Harry Potter for less than $10 apiece...but if you're just getting it solely for WW, by the time you get all the accessories it's the same as if you'd bought TP new, basically.
The memory card comes in different increments, from 51 - 1000+ blocks. WW takes 12 blocks, Animal Crossing takes something like 58...so it depends on which games you want to play. I think my card is 255 because the games I wanted didn't really need a lot of memory. Shipping was about the same as the cost of the item wherever I looked - it probably has to be packaged carefully (or I didn't look hard enough). The Gamestop worker I talked to said that they do sometimes get memory cards in, but because they're used, it just depends on how often they're traded in, and I didn't want to wait.
Gamecube games aren't on the VC because I think they'd take up too much of the Wii's storage space. The VC has LoZ, AoL, AlttP, OoT, and MM. Like Zeruda says, you could also look for the Gamecube collector's edition with the games she mentioned. I've seen it run for about $30. There's also an OoT Gamecube edition that has it and the Master Quest. It goes about for the same price (maybe cheaper, that's just what I've seen.)
In order to download the older Zelda games, you'll need Nintendo Points which you can either buy with a credit card or in stores. No tax applied to them in stores, I don't know about online. $20 gets you 2,000 points, the prices of the Zelda games on the Virtual Console varies.
I need to start buying from stores! They charge tax in my state online.
ETA: It may depend on the place, but they definitely charge tax on my Wii Points here (2000 points ends up closer to $22), so you may want to look it up where you live. Probably it pertains to if you pay tax when you buy online in general.
I forgot to add - I know it's not what you asked, but something I've learned is to unplug it during a storm! Probably seems obvious because it's an electronic device, but still. It's not pretty when the power goes out over night and you try to turn on your Wii the next day and it just blinks at you instead of turning green. You can reset it, but why risk the heart attack? (A decent surge protector is also recommended for that reason.)