Since gaming, graphic design and data mining aren't listed as it's primary function, you really don't need to get a top of the line model.
If you are into downloading stuff you need more storage instead of memory. For laptops and desktops, the term memory usually refers to DRAM, which you won't be able get 500G+ DRAM with your budget.
Since you are getting a EHD, you may consider getting an SSD for your internal hard drive. It will increase system performance. However, do not download large files directly to your SSD, always make sure you download to your EHD, as an SSD has a limited number of times you can write to it, and its performance deteriorate the more you write to it.
GIGABYTE P15F v5, with i7 processor, 128GB PCIe SSD, 8GB DDR3 DRAM, for $30900http://24h.pchome.com.tw/prod/DHAV39-A9006V95Q
For this one you need to shell out to upgrade to 512GB M.2 PCIe SSD, and you can get additional internal HDD upto 2TB. If you choose to do that, the price would be closer to $40k. It will be a gaming grade laptop with an Intel i7 processor though. By the way, better performance usually means less battery life.
ASUS N551JB-0052A4200H, with i5-4200H processor, 24G SSD, plus 1TB internal HDD, 4GB DDR3L, for $30900http://24h.pchome.com.tw/prod/DHAFEB-A9006TE90
ASUS Zenbook, with 256GB SSD, 4GB DDR3 DRAM for $25900http://24h.pchome.com.tw/prod/DHAFBJ-A9006QCOX
Same model with Microsoft Office for $29500http://24h.pchome.com.tw/prod/DHAFBJ-19006WW0S
Fujitsu LIFEBOOK UH554-UB523 with 256GB SSD, 4GB DDR3 DRAM for $27980http://24h.pchome.com.tw/prod/DHAM0C-A900682QZ
Just to name a few...