I happen to collect currnecy, among other things.
1. High denom notes ($500, $1,000, $5,00, $10,000) are not illegal to own, and small size one are still legal tender, althugh you would have a hard time spending one as they were last printed in 1934 and have been actively removed from circulation since the 1960's(?). What this means is that when a high denom notes gets to the bank, it is sent to the fed and destroyed.
2. All of these notes sell for maore than face value. Except possibly a single issue of $10,000 that were canceled and never circulated.
3. I suspect that whover contacted that person mentioned in the thread was being misled into giving up their notes to someone who knew what they are actually worth.
4. $100,000 bills were never ciruclated, they were used to secure "overnight loans" between banks, if a bank dropped below its reserve requirement. THere are 12 of these, all gold certificates, and all accounted for in a federal vault somewhere.
5. you have the best luck trying to loacte these at a coin/currency dealer. Some suggestions are:
http://www.donckelly.com/sm_type/sm_type.html#FRN scroll down to the desired denomination
http://www.kyzivatcurrency.com/catalogue2a.cfm?McatID=60#HIGH%20DENOMINATION%20NO TES
and for higher end stuff
www.jhonecash.com
I would suggest small size notes, as a general rule the older the series, the more expensive it is. IF you have any questions please feel free to ask. COndition, issuing district, serial number and centering of the note can affect the value of the note. If you have any questions feel free to ask.