timeUnit
Before I start, this is my opinion, based on my experience. I had to say that, because folks in the US are likely to disagree with what's coming.
I have worked with several 4x5 enlargers. The Beseler 45 is the second worst, only the Omega D-series is worse. Compared to the others, I have worked with, they don't have the same rigidity (while trying to be diplomatic, I have avoided to use the word 'flimsy'). Sorry folks, just my irrelevant opinion. However, they are very popular and common in the US. I'm not sure why, but if people like them and they work for them, why not?
To me, better 4x5 enlargers are the Durst L1200 (very common in Europe), the Zone VI (not as flexible but built like a tank) and the LP ? (forgot the product description).
Now to the cameras. Unless you wont to stay in the studio, hands off monorails. They are too bulky. For landscapes a metal-field camera is very flexible. I now have a Toyo 45 II and a Linhof Technikardan. Both are very good, but the Linhof is sensitive and twice the price, but has more bellows-draw (better for portrait and architecture). The wooden-field cameras are also OK. To me, wood is not the ideal camera material, but they are very pretty and work well if kept well.
By the way, don't be fooled by large adjustment numbers, advertised by the camera manufacturer. The bottle neck of adjustments is the lens coverage. Most cameras allow for more adjustment than what the lens can cover. I opted for 90, 135 and 210 mm focal length.
To the price. $900 for a 4x5 enlarger is too much these days. I would not pay more than $500 for a mint version, and with enough time to wait, you might get one for free, if you are willing to go and pick it up. Expect to pay up to $1000 for a good 4x5 camera, used. Good 6-element enlarging lenses cost about $200 new, but for 4x5 you might have to pay more. You should get used ones for a fraction. Taking lenses are $800 and up, new, and about half that used. Again, mint only. Go for Nikon, Rodenstock or Schneider for enlarging and taking lenses, and you can't go wrong.
Again, just my opinion, that's all. Your experience may lead you to different conclusions.