Bigfoot,
If I were you, I would try really really hard to get a used PSR550 or even the old PSR740 (loaded with pro features) from one of the synthzone members or somewhere reliable. The new PSR550 can be had for $499.00 at music123.com Maybe you can get a used one for $200-300 if you're lucky. If you're really lucky, get the even newer PSR1000 for that amount of money. I bought my PSR2000 for $550 and I am set for the next 5-10 years.

If not a new one even a used PSR350 is much better sounding than CASIO WK1630 or 1800. These are older keyboards but they have all the essential features that we've been talking about here. When you amplify the keyboard, it sounds decent and much better than CASIO - warmer pianos, etc. Can't go wrong with those older models.