GEM 504?
I would be very happy to sell you my old GEM 504. It served me well, but you should update/replace/repair the light head, which is not in a good condition, though it still produces light.
GEM 504 is closely based on DeVere 504 design, e.g. it has focusing and lift knobs at hand level by the base board. It was made in UK by a group that splintered off from DeVere. They are sturdy and nice, but they are not as excellent as DeVeres have been, in my opinion.
The head is a cold cathode also made by GEM. It is old and there are scratches on the milky plastic diffuser (you cannot see the scratches in the attached pic but they are there believe me). The tubes are also past their due. If I were you I would either stick another head on it (used Ilford 500?) or consider replacing with a new cathomag - Aristo in US sell those. Nevertheless, you could have some immediate fun with the head, especially if you like the idea of a cold cathode.
I am based in Co. Wicklow, so if you can collect (it weighs some 50kg) you would avoid paying high shipping costs for the heavy part of an enlarger. If you decided to replace the head at some stage that would save you money as heads tend to be lighter and smaller than the really big 5x4 enlargers.
This GEM comes with glassless negative carrier for 4x5 and a lens board.
So far I kept this beast for sentimental reasons. Besides, putting it on eBay would not make sense as shipping such a heavy thing would be really pricey. So I decided to wait for someone in Ireland to perhaps want it one day.
If you are interested, let me know your offer and when you would like to see it - I will be most reasonable.
Rafal