White / Pink / Black /
Carbon Fiber (all 'synthetic' leather') cases with magnetic latch on eBay for $9.49 buy-it-now with free shipping.
A
variation with a belt clip is there for the same price, as well.
PDAir makes a what looks to be a nice, genuine leather flip case as well, for $29.99 shipped.
In terms of a 'premium' leather flip-style case, the only ones I've seen are by
Noreve, and run about $60 in black. There are lots of customization options (color, patterned, bonded, with belt clip option, etc) that can drive the price up to as much as around $90 -- plus about 2 weeks production time.
Edit.. did a quick google and came up with
this site, which probably has every option I listed above and countless others.