Is there a reasonably priced vehicle mount to an AR15 under a trunk lid or in a truck box?  The in-vehicle mounts from a police equipment supplier are over $200, which is way more than I want to spend.

I don't have an answer for you but I do have a question ...  What supply store did you check that had the mounts for around $220.00?  Was it on the net?

you could do the job with some velcro... maybe? Dont really understand the question.

Check Surplus stores for old jeep mounts. Cant be more than 20 bucks.

The US GI vehicle mounts are out there.  I found a set for about $15-$18 on Ebay a while back.  Nothing fancy, just a socket for the butt that you bolt to the floor and a spring-loaded J-hook and rest that bolt to the dash or side of the vehicle.  Probably not a great choice for most civilian vehicles, and no security features whatsoever.

A friend used one of the back-of-the-bench-seat organizers in his pickup.  Had a tubular rifle/shotgun/fishing pole carrier running the length of the seat.  Stored upside down and muzzle end in he could draw it from behind the seat very quickly as he stepped out of the vehicle, while it remained out of  sight otherwise.  Think he could only fit a 20 round magazine in it like that though.

I don't know if any of the hunting rifle/shorgun trunk mounts or overhead cab mounts will work with an AR; suspect they're too narrow.  I would be inclined towards a locking container of some sort rather than a police-style mount, unless you're sure you'll never be leaving the rifle in the vehicle and/or immediate access while inside the vehicle is important.  When I carried a rifle on patrol in a Cherokee or Jimmy it just sat in a soft case, muzzle down by the radio stack.  If I was going to be more than 20 or 30 feet from the truck the rifle would be with me..  _Very_ rural area; I wasn't too concerned about anyone being able to reach into the truck while I was busy in the vicinity, and if I was away from the vehicle I was probably going to be well away from it and in terrain where a rifle was the appropriate weapon.

For police style mounts, check out www.galls.com or www.streichers.com.

Thanks for the thought on behind the seat hunting style mounts.