amazon.com - Viking 256 MB CF for $35 after rebate
ecost.com - Click on the Bargain Countdown tab and scroll through to find the CF deals. There is usually free shipping but there may be a small handling fee. They have a Kingston 128MB CF for about $10 after rebates.
These sites below find good deals. Just search through them for 'flash' or 'CF' , etc:
www.techbargains.com
www.bensbargains.net
There are other threads in this forum that mention which cards may give you problems. Also read Amazon's customer reviews.