Decent indoor shotgun?
 

I have an

ME 66
a Rode NTK
a pair of NT3'S

but looking for something that works well for run and gun indoor videos. I have a budge of about 2k but I'd like to stay around 500 so I can spend about 1500 on some lav's later.

Have you considered the AT4053?

"Indoor shotgun" is almost an oxymoron. The problem using shotguns in a normal interior (as opposed to a soundstage or other acoustically controlled environmment) is not the quality of the microphone, it is inherent in the physics of the interference tube principle that shotguns use to achieve their directivity. There are two issues - the directivity is frequency dependent and more importantly, the interaction of the on-axis direct sound waves and the off-axis indirect reflected sound waves inside the interference tube leads to some frequencies being supressed and others enhanced, causing signifigant distortion to the timbre of the recorded sound. That is why for normal interiors a hypercardioid or supercardioid mic is generally recommended. Exteriors and acoustically controlled soundstages don't have as strong a close reverberent field, hence the problem doesn't occur. Hsien's suggestion of the AT4053a is a good one to consider. Also the AKG Blueline SE300/CK93 (~$500) or ULS C480/CK63 (~$1k) modular combinations with the hyper capsules are worth a look-see. If your budget would stand it, the Schoeps CMC641 is arguably the industry standard.