Tv museum doesn't have ads? Looking for rca 621 also.

Pre-war TV's rarely come-up for sale. Often collectors get wind of one before it's even advertised and make a quick deal. When they do come-up though, if it's complete and with a good CRT, prices are in easily in the $5-10,000+ area.
621's go through phases where they're for sale fairly often, and then nothing for a long time. You have jump at an opportunity when it comes. A real nice one will run up near $1,000.

I did a google search and came up with this one on Craigslist in London, UK.

http://london.craigslist.co.uk/clt/5433550164.html

Be careful about ads like this. No pictures, text seems like it is copied from a website. An owner of a prewar set with that much knowledge would know that Craigslist isn't the place to sell it.

Place an ad on on classified pages saying you are looking for a prewar set. There are people out there who are interested in selling but haven't gone public.

Steve is right. That text came from a 2011 Worthpoint posting showing the source as an online auction in the US.

http://www.worthpoint.com/worthopedia/1938-marconi-707-pre-war-television-154642070

You can often track these fraudulent listings by taking a sentence out of the text, putting it in quote marks, and doing a Google search.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=%22does+not+appear+to+be+a+speaker+in+the+set-at+least+I+don't+see+one+in+place+behind%22

.

There's a 621 listed in the ETF classifieds, it's from August of 2015 though so it may already be gone.

About halfway down this page:
http://www.earlytelevision.org/classifieds_postwar.html

Obvious scam advertisement. We've had problems like this in the UK a number of times.

I am planning on making a replica prewar with an 80's black&white tube tv. I have a couple 'simple' design models picked out to replicate. I don't plan on destroying any tube radios or post war sets in the process.

I looked-Admittedly, not all that hard, for a 621 for 25 yrs B4 I latched on to the one I have now. Need to take it to Terry in Knoxville, however. Prolly as close as I'll ever get to a prewar set. But that's OK, 621s aren't exactly common, by any stretch of the imagination.

There was just one on ebay that I think didn't go that high

There was just one on ebay that I think didn't go that high
A 621? They used to be up in the $1,500 range and then seemed to be selling under $800. I've seen one sell back up in the $1,000 recently, so I think that's what a nice working example should be at. In a private sale from a collector you should expect that price. Auction prices are always up and down.

I pretty much plan on making a one-off prewar set out of a 1980's portable 5" zenith set and some time in the woodshop. I restore radios like the rest, so I dont plan on destroying a console or table radio for this project. I think there are some easy enough designs to mimic.

I pretty much plan on making a one-off prewar set out of a 1980's portable 5" zenith set and some time in the woodshop. I restore radios like the rest, so I dont plan on destroying a console or table radio for this project. I think there are some easy enough designs to mimic.

I think I've seen something like this on eBay before.

There were some old prewar magazines with articles on how to build a TV kit using the one inch 913 CRT. There is a modern writeup here how to drive a TV signal from the 913 CRT and other older eletrostatic CRTS using modern electronics. http://www.labguysworld.com/Project_ESCRTs_001.htm
Some of the older oscilloscopes which contained these CRTs can be seen here.
http://www.myvintagetv.com/vintage_test_equipment.htm

There are several prewar radios with a round dial face which could be gutted to turn into a TV cabinet.

Here's the thread where we were talking about one of the replicas on eBay.

http://www.videokarma.org/showthread.php?t=258841

1938 Articles describing television circuits required for 1 inch (913), 2 inch (902), 3 inch (906) CRTs.

http://www.earlytelevision.org/pdf/building_tv_rcvrs_qst_1939.pdf

picture is of a similar 1937 TV Kit found in 1937 edition of Jones Radio Handbook.