I have used and owned Saunders LPL 66 & 67, Omega D5, and Bessler 23C III. All are good enlargers. I perfer the flat neg carriers of the Omega and Bessler - easier to make them full-frame or to change the aperture for different formats. The Omega focuser is a pain, but you get used to it.
I would jump to a medium format or large format enlarger. They are built better and you are all set if you try a new format. If you are not attacthed to a condensor head, get a color head. Not only can you do black and white printing with it on graded or multi-grade paper (just dial in the filtration and that means not hanging filters in front of the enlarger lens), but you can go to color in the future.
About the prices you quoted. You should be able to get a good, modern 50mm enlarger lens off ebay for about $30 - $80. I picked up a Rodenstock Rodagon 135mm for $70 (4x5), an APO Rodagon 80mm for $100 (6x6), and a 60mm Rodagon for $75 (35mm). You should be able to get a 50mm for under $100. Rodenstock, Schnieder, and Nikkor EL are all fine lenses (I have used them all). Make sure it is a 6-element (or greater) design - Rodenstock and Schnieder have a 4-element economy lens. You should be able to get the lastest versions off ebay - check the manufacturer's web site for names and specifications.
I have bought one enlarger from ebay. First, enlargers are simple machines. They are easy to fix and they are not difficult to align - unless it was "unaligned" by a large fall or hammer. Don't get anything that shows chemical stains. I was able to get a nice Omega D5 with a color head. The problem is not the enlarger, it is the shipping. My enlarger arrived with the negative stage bent in half and the lens stage ripped off the rails (and packed in what only can be described in garbage - it took me two and a half hours to clean up the "packing" material). Not the happiest of days. But for about $30 in parts, I fixed it up and it works tickety-boo.
BTW, try to get a good grain focuser. Peak make excellent models. I have use both model I and model III and they are very good. Omega repackaged the top-of-the-line Peak grain Focuser and goes by the name Mircomega. They can be had for less than the Peak version because fewer folks know about them. BTW, I think the Bessler HD enlarger lens line is the same as the Rodenstock Rodagon (they look the same too) and go for a little less as well.