Your poll doesn't make much sense to me. What costs are you asking about? The tax cost? I'd vote that I will own items regardless of the current stamp price as long as it remains at $200, but that's not an option. Adjusting it for inflation may make my answer different. Your poll is too narrow IMHO.
That said, here's how I'd change the NFA (other than completely repealing it)
1. Make some sort of PIN available to 'frequent flyers'. There's no reason to have to go through the entire background/fingerprint process for the same person who submits paperwork within a matter of months of each other.
2. Remove the '86 machinegun ban.
3. Remove import restrictions on machineguns which would be legal under NFA registration.
Silencers have NEVER been illegal !