I just got done spray painting the driveshaft and rear pumpkin on my 67 Thunderbird that I'm restoring. I used that automotive paint from Oreilly's that's like $7 a can. Sanded them down, put on 1 coat(no primer or clearcoat) and 4 days later I put the driveshaft on. Did all this in just above freezing weather. You can't even scratch it with a fingernail. I plan on doing several bikes this way come spring. Sure it may not be quite as durable as factory, but it's still more durable than what most people think. If you can get your bike powder coated for $7 then by all means do so. Until then I suggest using that automotive paint instead. Your color choices are somewhat limited though. I recommend the aluminum color as it looks similar to something you'd see on a 70s era bike.