Are you looking for an XC style low travel or more All mountain oriented? I would say with that budget pick up some carbon wheels ~800, carbon frame ~800, all-new sram NX eagle ~375, decent fork ~500, decent shock ~250, okay brakes ~125, and then all the other knick knacks. That already totals to about ~$2850. To stay under budget you don't have to get the carbon wheelset, but its nice.
Brands to be looking at for frames: Hongfu bikes, workswell, ICAN, Dengfu, xmcarbonspeed.cn
Brands to be looking at for wheelset: lightbicycle, farsports, yoeleo
The main thing im struggling with in building 2 of these bikes, 1 HT and 1 FS, is the damn shipping time. Some people get them shipped in a few weeks. It's been 30+ days and I still haven't got a tracking number, so you know, its relative.