As far as real world value goes, I would bet it won't bring more than $5000. Here in the Atlanta area, VERY nice stock 99-01 4x4s with low mileage sell pretty consistently around 4k. I recently sold a very well built charcoal grey 2000 Classic with a 4.5" Rubicon Express long arm kit, 33" Duratracs, winch bumpers, Bushwacker Flatfenders and 4.10s. It sold for $3950 and it took me about 4 days to sell it. I met lots of tirekickers. It had near perfect interior and exterior, every option/accessory worked and it had 198k miles.
If you find the exact right guy who loves everything about it, it may be worth more but I've found modified XJs to be harder to sell than stockers. Anyhow, just my .02!
'Lots and lots of XJs'
Daily driver: '00 XJ Limited 4x4 w/ 300k miles and still going strong.