Door Latch
The $20 solution may be cheap, but I think it is not safe. Any latch should be able to be opened from the outside in the event of an accident. In the last year we have had 2 flip-overs and had to pull out an incompacitated pilot in one. Don't assume that the tools to break thru a door will be present.
Also, opening the latch prior to an off-field landing may make sense in a skyhawk, but not a 10. In the stress of the situation it is unlikely that you will remember to do it, and if you did you will have to contend with flying an airplane with 2 doors that have just departed. It is folly to think that you can plan your crash ahead of time, sometimes it just happens fast. I would not want to be locked in a cabin with gas leaking all over me.