I need help on building a workstation for game design/3d Modeling/rendering and some gaming. Software that I’ll be using will be Unity 3d/ blender. My budget is $2000 to $2500. Also any recommendations on a good Ips monitor and video card.
Any advice that can be given would be greatly appreciated.

Hobbyist? Pretty much, any halfway-modern computer will do as long as you give it plenty of RAM. As a hobbyist, you probably won't be pushing the number of polys that the pros do, so going super high end is probably just a waste of cash. I'm on a shitty HP box from Costco, and I have no problem doing medium-level character sculpts of around 250,000 triangles in Blender or Sculptris. Get a graphics card with good OpenCL support, and Blender can use it for rendering pretty nicely. We've gotten to the point where consumer-grade mid- to low-end hardware is more than enough for anything a hobbyist game developer is probably going to throw at it.

Are you gonna buy it whole or build it yourself?

What resolution monitor are you aiming for?

What modeling programs do you plan on using? High poly or low poly?

Do you multi-task? Keep multiple apps open at the same time and switch between them frequently.

I concur about the RAM advice... at least 16GB.

We've gotten to the point where consumer-grade mid- to low-end hardware is more than enough for anything a hobbyist game developer is probably going to throw at it.

I'm not sure I agree with the low-end part, and even the mid-range parts don't include big power supplies so if he were to wanna upgrade his GPU he'd need to upgrade the power supply as well. So if he goes with a pre-built machine he should look for brands that have an option for a big power supply like cyberpower.

It greatly depends on what you're planning on doing. 3D modeling/rendering is very vague. That could mean intensive CAD/CAM or just a guy playing with Blender in his spare time. One could require a graphics card in the $2000+ range and powerful CPU. The other can be done with a standard enthusiast level card and processor.

What are your SPECIFIC goals?

My current system is an AMD 8150 with 16 GB RAM and a XFX 7870 GHz edition GPU. I can play any game on the market and use Blender regularly. I could even use more advanced 3D software without pushing my system too hard and I built it three years ago. It cost me less that $1000 when I built it. $2000 to $2500 would allow for much more powerful, but possibly unnecessary, options.