If I'm lazy and just want to use a ziplock bag (without coupler), I cut the corner, put the tip down there, and then sellotape firmly around it. I've never had one bust, but don't squeeze too hard just in case. I do find the sellotape really helps secure it though and it doesn't slide around.
Otherwise, I agree with what others have said.... you could just get a washable pastry bag and that's just one expense over and done with, you can use it as many times as you wish. The only problem is they can be a pain to wash out with the grease.
Personally if I were you, I'd just get good disposable ones online. Be careful of the really cheap ones... although I was lucky and mine were cheap but good.