There are two ways to look at this....The first, ever since my early days of RC I was told if you are out of the pattern and have a mid air you are at fault.....that would be flying CCW when the pattern was CW or crossing the field like in a figure 8. You said the other guy was out of the pattern. Was he in the middle of the field?
The other way to look at this is...if you were to try and have a mid air you would find it very difficult to hit another airplane......so it must be an act of some divine being...you must have angered the RC Gods.....seriously to try and hit another airplane is almost impossible.
So now the real question....let's say he is at fault.....how do you get him to pay you 300.00 bucks?
The best you can do is complain to one of the club officers, about all they can do is talk to the guy, or at the worse kick him out of the club for some kind of a conduct charge. That won't happen and you still don't have 300 bucks....
In my opinion it would probably be best to look at this as all airplanes have expiration dates and I found mine....When this guy goes up I come down....
Sorry for your loss, Good Luck
I just had another thought....sounds like there was no communication between the pilots flying...whats wrong with telling the other pilots that you intend to do a touch and go, or I'm gonna do a loop on the downwind, I was flying yesterday with a 3D pilot flying a 35% Yak, we kept each other informed, he would tell me as I turned up wind that we was in a hover over the grass.....Or has he was hoovering I would tell him I was doing a Cuban 8 on the downwind.
Even if no one does this at your field now I promise if you start to do this the other pilots will also start to do it as well.