Chicago Carburetor rebuilt my Nikki for around $200 plus shipping
This is a pretty reasonable price if you consider the cost per hour charge and any parts. So say 2 x hours at $85 + a few gaskets, pins and clips, not to mention the pics Conner posted of his refurbed carb were very impressive and I do not think the average person could get one that new looking.
If you chose to DIY, it's pretty simple. Deerio's laser cut gaskets are spot on accurate and sure beats tracing and cutting your own. For the clips and pins your local hardware store has most if not all of them in the yellow plastic Servalit boxes in or next to the nut and bolt section. If you don't find the exact clip or pin do not forget to check the plumbing and lamp section for additional yellow Servalit containers. That big round rubber float bowl ring is up in the plumbing section - just do not forget to take your carb with you to get the correct fitment and size. I want to say 3 1/8. I have one on my DD '65 and its still doing great after 15 months.
For disassembly I recommend separating the three main sections, removing the jets and emulsion tubes and what ever else you are comfortable with. I DO NOT recommend touching the springs or the butterflies (and a good reason to send off to Chicago Carb if work is needed here). From here is just a matter of boiling things for a time and cleaning up those calcium looking deposits. More than likely your float bowl section is all discombobulated from wrenching down those glass retainer screws. I tightened up a crescent wrench and bent those screw tabs back into place - ever so slowly and carefully. Used a straight edge to check the clearance and called it good. The carb is made of pot metal/white metal and near impossible to repair so go easy and evenly from each of the 4 screw tabs.
Don't forget to take plenty of pics of the before and disassembly process to aid in reassembly. There is not much to adjust on the Nikki carb except the mixture and idle screw. So pretty simple to get running again at almost any setting and then just fine tune from here once back on the manifold.
cheers
Andy