I am getting into photography. I have been doing videography for about 3 years with my go pro and iphone and am looking to upgrade to a DSLR Camera that doesn't completely break the bank
In addition to taking sick photos, I need it to do the following
1) Capture 4K Video
2) Has an input for an external microphone
Budget is around $1000-$1500.
Go to your local camera store and check the used cameras on stock. They will be great. As a Canon user, I would say that a 5DMark4 would be great, a Mark3 does not do 4k video. You can also go for a different brand: Nikon, Sony…, but I would stay in the full frame range.
Please keep in mind, that you also need good lenses, and if your budget also includes the lenses, that it could be tight.
What is a good lense to pair with this camera to begin with.
I use the Canon 5D Mark IV primarily with a Canon 24-105 F4.0 L lens which has been my favorite lens for 10 years, mainly because it's a great travel lens due to the focal length range. If you're in the U.S., CraigsList.org might be a good resource for used cameras / lenses, particularly since many photographers are updating their gear to mirrorless.
I'll just add to this - really, keep in mind getting good lenses. Better to get good lenses and an ok camera, rather than a great camera and ok lenses.
Another thing you should also consider is looking at Mirrorless cameras. They are lighter than DSLRs.