[quote:301838b48a="drx"]Most companies don't, in fact, have vaults. Most consider protos to be trash and they're dealt with accordingly. Very few companies treat prototypes/builds/archival seriously.[/quote:301838b48a]

as sad as this statement is it's true after the final revison of a game is released most companies see no need in keeping older builds of said game anymore which is a shame because it's a nice idea to keep stuff like that around to help preserve the history of the game during it's development cycle (you'd be surprised how many people feel this way)

[quote:301838b48a="drx"]Some developers have kept prototypes as keepsakes, or because they had some on their desk when they were packing up to move, etc.[/quote:301838b48a]

If a developer is proud of their work they will more than likely keep a beta or two for memorial purposes some might keep betas for other reasons like retweak the game engine translation etc. 

[quote:301838b48a="drx"]It usually takes years (yes years) of patience to get a particular prototype from a non-collector.[/quote:301838b48a]

If by noncollector you mean the developers themselves then yes it's extremly hard to near impossible to get a beta from them

[quote:301838b48a="drx"]Then there are collectors like me who have protos they themselves found or bought from other collectors.[/quote:301838b48a]

Thats true but there are (to me at least) two different kinds of collectors out there 

1. collectors who have unreleased betas that usually keep them for themselves and are usually non-negotiatable when it comes to releasing these betas (here's an example: http://forums.hidden-palace.org/viewtopic.php?t=2818) which sucks because they could be contributing to the archival of games from the past.

and 2. collectors like drx who are willing to release such betas under certain conditions (ie getting a target amount of money through funds or things like that)

because collectors like drx are willing to help preserve the history of video games they are highly respected among retrogamers such as myself.