The Wollensak Velostigmat 300/4.5 was available in a soft focus version, which was sharp until you crank out the front element and it becomes progressively softer. They show up on Ebay regularly and are within your price range. Basically, it's the same lens as the Xenar, but uncoated. Being a normal lens for 8x10, of high quality. it won't give you the vignetted, falling-apart-at-the-edges Sally Mann look, though, and neither will the Xenar. Perhaps using one that's too short for the format will make you happy, though, in which case I might start with an old 165mm Wollensak (probably around $70 on Ebay). Unlike modern lenses, these Tessar-format lenses get crummy at the edge, beyond their spec'd format, before the image circle runs out, and that test would be within your budget.
For her look, you might look for a projection lens designed for a smaller format than 8x10, then figure out what to use as a shutter. I like Packard shutters a lot, myself, so don't write them off.
Another option is fitting a close-up accessory lens to a spare shutter. I have two old shutters that fit 49mm and 58mm close-up lenses, and a set of either runs about $15 on Ebay. That's not the Sally Mann look either, but it's cool. On LF, because the relative diameter of the lens is small, the effect won't be extreme--go check out the flickr.com monacle group--
https://www.flickr.com/groups/monocle_lens/pool -- for some examples on 35mm format, which is more extreme. Reinhold makes the exotic version of this, faster than you can hang on a small shutter, with therefore a greater effect, for LF. I have two, and they're well worth the cost:
http://re-inventedphotoequip.com/Home.html
Bookmarks