Yeah anodizing titanium hardware is fairly easy. You don't even need a tank you can just use aluminum foil, baking soda, and a paper towel to brush the color on.
The hard part is prepping a large smooth surface and getting that to look good. Or getting specific color shades to show up well.
If I was using titanium bolts for projects saving money using a 9V battery to anodised them would be a little daft.
Yes titanium bolts are expensive but custom color anodized ones more so, not sure what you are getting at here.