I have seen similar domains sell to end users for between $250-$750 so I would agree with the low to mid $xxx valuation, but I don't think the letter combination will go into the $xxxx range. This is just my opinion, but I have over 400 LLLL.COMs and have yet to see one of this type go for $xx,xxx. The market seems to be trending up in price for LLLL.COMs, so I would be happy to see it go high!
Good Luck!