How are people mining at 148,000 kh/s? Are they running a farm of CPU's?
the more likely they are using cloud instances (Amazon or other). Or people who works in hosting company, etc..
Amazon cloud isn't cheap... high usage CPU instance that might get you 400KH/s would be around $0.60/hr. Even at 30LTC/1000YAC, that's like 3LTC/day for $14. $4.80/LTC...