I see no premium above reg fee unless all 4 letters are the same. Even then, it's a novelty name, unlikely to attract type-in traffic and prone to mis-typing (hyphen misplacement, dropped or added characters) when someone goes there intentionally.
As far as rarity for 4 letter and 1 dash domains, I don't see them being valuable for a long time. Have you looked into L-L-L.com or L-LL.com domains? They both have potential and are currently undervalued.
4 Letters and a Dash (5 Characters)
456,796 L-LLL.com
456,796 LL-LL.com
456,796 LLL-L.com 1,370,388 Total
3 Letters and 2 Dashes (5 Characters)
17,500 L-L-L.com Total
3 Letters and a Dash (4 Characters)
17,500 L-LL.com
17,500 LL-L.com
35,000 Total