You Cant
Buy one.
Yeah, there are new guns coming out all the time. They may not be all original in design and function, most of them are just upgraded versions of what we've already. They may add new cooling systems...
No. Generally, you can expect a 10 - 15% reduction in value for a used gun, more with increased wear and tear.
This is an internet rumor that has been around for years that is completely false. Check it out on snopes.com