> 2. Wants it to feel as close to piano as possible.
> 3. Budget - $200 max
Mutually exclusive goals there, mate.
A weighted action keyboard that feels like a piano is usually 76 or 88 keys and upwards of $500.
61 keys &/or under $200 are almost always unweighted "organ" style or at best "semi-weighted" keys.
Check out M-Audio
Keystation Pro 88 - the feline's sleepware but lists at US$599
http://www.m-audio.com/products/en_us/KeystationPro88-main.html
Keystation 88es - semi-weighted and list US$299
http://www.m-audio.com/products/en_us/Keystation88es-main.html
Keystation 61es semi-weighted as above but 61 keys list US$199
http://www.m-audio.com/products/en_us/Keystation61es-main.html
Other brands: Roland, Studiologic, Fatar
Go to a music store (not a computer store) and see if you can try before ordering. As a pianist, you wife will probably say "Eeew" when she tries an unweighted keyboard. Much of a piano's expression relies on the subtle variation of finger attack the pianist can control when the key "pushes back" in the right way.
Another issue is latency. When you play a MIDI keyboard into a computer, it takes between 3 and 30 thousanths of a second for the computer to get the message, activate the sound synthesis or sample engine, translate it from digital to analog, and push the audio out to the speakers. The faster the computer, the better (or simpler) the software, and the better the D/A interface, the lower the latency. At higher latency values, the player definitely feels that their fingers are "disconnected" from the sound - "I hit the key but the sound doesn't come out 'til later".
If this is a problem for the player, the solution might be to get a keyboard with built-in sounds for faster live response while playing, plus the MIDI &/or USB connection for working with Garageband etc. More money, of course. You might be able to get a used MIDI electronic piano; but these will almost certainly lack the USB connection, so you'd need to spend extra for a USB-MIDI interface.
Last bit: unless you use decent headphones, the piano sound is going to suck. Badly. The dynamic range and the frequency range of a piano is far beyond the capability of computer speakers and inexpensive Hi-Fi speakers. Be prepared for another trip to town on the next weekend for better speakers...
Thanks
Trevor
CanadaRAM.com