Try MetTec...Ti bolts are very expensive but these guys are about 2/3rds the cost of McMasterCarr and less in some cases. Delivery was around 5 days or 5X longer than McMaster. I replaced the whole set of steel bolts on my DLE55 with Ti (around 40$), and shaved about 1 1/4 ounces. These were 5mm bolts (about 10-32 size) which are heavy and the heaviest and most expensive were the two 60mm carb bolts. Didn't have the guts to try them on the prop tho...those 4 bolts are also heavy and aircraft Ti would probably work okay there too; just too chicken to try them

For electric stuff, why not use aluminum bolts? In my search for strong and light, I've saw some Ally aircraft alloy bolts with rather high tensile strength (probably more than adequate for e-stuff). Ally is around 2/3rds the weight of Ti at 1/3 the cost (I think that's right). Met Tec is one decent source for Ally bolts too. My search was not exhaustive by any stretch and I had no interest in Ally alloys so I didn't dig very deep. I could be a little off in my estimates.

For a really snazzy look, take a look at their anodized colors, but these are even more pricy