I found a considerably easier method to obtain the BP/FP/EP/DP Merit in the mission "555 We Tip" which doesn't require any resources or cheats. Basically, after several unsuccessful attempts in trying to flip over the Merit with a Forklift, I ended up noticing that the Doherty garage is rather close to lots of uneven ground, where flipping the car by simply driving it upside down could be easy. However, after not succeeding much, I found an even better spot to flip the car - the ramp directly west of the garage. Just slowly drive up it with both your left tires off the ramp and it should soon roll over.
Get away from the car as it blows up, then push the wreckage to the garage. It's easier to push it actually sideways, and even easier if you have a vehicle of your own to do the pushing. Preferably get it before flipping the Merit, and park it someplace nearby, as the wreckage may disappear if you focus your attention away from it for too long. Just remember not to close the Merit's doors when outside it at any point, or they will lock and even parking it in a garage doesn't open them, which forces you to pretty much push it up the ramp to somehow still flip it over.
Let the garage door close and re-open, and there you go. A Merit with all the proofings, ready to use. No need to get the sluggish Forklift all the way to a garage from Easter Basin, even if the trip is rather short.EDIT:
Also, note about Berkley's RC Van. It's indeed not unique, I just jacked one in The Fallen Tree (around the border of Red County and Flint County) so they spawn regularly in traffic, just that they only spawn in specific areas, the Desert apparently being another place for them. Of course, sometimes they might be scarce, but that makes them only rare, not unique.EDIT2:
And again. This time, it's the Light Blue Pony in Toreno's Last Flight. A potentially easier way is to simply kill the 4 guys (+ the cop who doesn't take your shooting nicely) then don't get up to the helipad, but just run to the Pony and drive it to a garage. Then return to the helipad and begin the chase like normal, shooting the chopper down with a heat-seeking RPG if you can, completing the mission. Therefore, it's not necessary to be quick in taking out the chopper while still getting the Pony.EDIT3:
Oh my... I just found light blue Pony's on the road, multiple times! First at Easter Basin, later near the Easter Bay Chemicals. This seems to prove that the car is not in fact unique, and the light blue color belongs to its usual palette.
Edited by Carbonox, 10 October 2011 - 01:02 PM.