I'm not sure I buy into the notion that cheap enlarger lenses work fine when they're stopped down. They certainly work BETTER when they're stopped down, but they likely do not compare well with high quality lenses.
In my past I've had two enlarger lenses that compared miserably to quality lenses. A long time ago I had an inexpensive Spiratione lens and more recently I had a Meopta Belar - both were visibly quite poor compared to more expensive lenses. I'm currently using a little Durst F30, exactly the sort of enlarger you described as wanting - and the lens (superb!) is a Componon-S.
Meopta makes a great enlarger (I have an old Axomat) and I'm told their higher quality lenses are quite good. If you get one, make sure it has a Leica thread lens board. Some of the older ones have a 23mm lens board.
I also agree with the one poster who suggested going with an enlarger that goes up to 6 x 6 (I also have a Durst M600), but the small footprint of my Durst F30 is a blessing in my make-shift darkroom, aka "the hall bathroom".