mehguy - It's probably been 20 years since any COMMERCIAL Durst has been available for sale new. There's a small possibility that a few 138's are still in crates in Italy. This was a completely different division than the 4x5 and smaller Durst "amateur" enlargers. True machined and diecast components; no anodized aluminum parts. That kind of fabrication would be prohibitively expensive today. Nearly the entire remaining inventory was bought up by a single dealer here in the US, including most of the replacement parts. He sold perhaps 200 units worldwide between 1990 and 2010, starting at around $16,000 apiece, and going up to around $90,000. But what he really was after was mandatory service contracts plus travel time, along with the initial sale and installation charge. This included Govt clients; 9x9 inch aerial film and spy planes were still in use at that time.
When his stockpile of new Durst 5X7 and 8x10 enlargers started running out, he made his own out of cannibalized components. He was an excellent machinist in his own right. But his business ethics were questionable (an understatement). He took deposits in advance, but then couldn't deliver, and in the meantime died. I have no idea what happened to all the leftover parts.
The Durst 184 control boxes were designed so that minor substitutions in the electrical components and outlet plugs would allow the same basic units to be sold in different countries with different standard voltages. So when shopping for one, you need to be certain it's wired for your own voltage, or at least be able to convert it yourself.
A wide range of light sources were made over the decades, including condenser heads and multiple generations of colorheads. I'd avoid the early CLS 300 2000W version, unless you're trying to beat the US back to the moon with something nuclear powered (those units run very hot). The subsequent CLS 301's are much more energy efficient and easier to maintain. The later generation 2000 W heads are quite tall overall and are expensive to buy.
I did convert one of my L138 5x7 chassis into an 8x10 cold light unit, which will fit in a room with a standard 8 ft tall ceiling. My other L138 was fitted with a "hot rod" customized 5X7 additive (RGB) pulsed halogen colorhead, which is in the same room. Now of course, one might opt for some kind of low-profile LED head; but it probably wouldn't have as much lumen muscle as a traditional halogen colorhead. The biggest advantage of LED is that it would run cooler.
But L184's need a minimum of 9 ft (I have a 15 ft ceiling in that room). I made a new laminated baseboard for mine, and had Custom Bellows in the UK make me a new bellows. After I either polished or repainted all the metal, cleaned the internal filters, and rewired the unit (one month of weekends for the entire project), I ended up with a 100% functionally restored unit, with around a 95% cosmetic restoration. It was a fun enjoyable project. I already had numerous suitable lenses.