I have looked for a decent XC bike, but not sure on what’s a decent hardtail now.
These days a lot of it’s about what’s available.
Do you want singlespeed specific frame or are happy to use a tensioner? I enjoy my Longitude geared but was thinking about singlespeeding it this winter to shed some weight and maintenance/cost. Best thing about the bike is it’s simple (geared or otherwise), it’s tough, comfortable, it carries anything and goes anywhere.
(There are a couple of Longitudes now on ebay within your budget)
I too was looking for more XC hardtail budget-conscious recommendations on here recently and Sonder Dial was mentioned often. Also On One Whippet