I think the presealable spawn bags are great. I also like the ones with the injection port. But all of these fancy things drive the price up many times. I have seen bags over a $1 a shot, and while it's not a lot of money for a few runs, it just isn't really necessary and does count up. After all when the bags come out of the cooker, the flaps should be folded down the side and sticking togther tight. All you have to do is be careful to not pull the flaps apart before you seal the bag. Once you have it sealed, it will be void of air so just hang it up with wood clamps to self-inflate (see attached picture). Then once it's inflated and cooled, you inject with liquid culture, seal the needle hole with hot glue, allow the glue to cool, and mix up the substrate by kneading through the bag taking care to never touch the filter patch. Those are the essentials to "my tek" (ideas which I borrowed from a dozen others) covering this topic on the Shroomery, although I have attached some pictures from the tek here.
As for the best bags for me, I am rather split between the 60-cent bags with the superior plastic and filter patch like those Fungi Perfecti sells and the cheapest 30-cent bags that Spore Works sells. The cheapies work okay but just don't have quite the quality plastic and filter patch of the more expensive ones (and they are a tiny bit smaller). If you are working with sharp stuff like woodchips, the cheaper ones can puncture more easily during the kneading step. Another thing that differs a lot between the two bags is the filter patch. The cheaper bags must be treated with a lot of respect because if the patch gets wet and you touch it, the bag is basically toast. The more expensive ones seem to resist this vector of contamination better. In any case, I take care to never touch the filter patches regardless of the bag and keep the patch dry at all times. For example, when you are injecting the LC, take care to not squirt it directly on the inside of the filter patch; that's just asking for trouble and I contaminated a bag that way.
I have been using hot glue for some time and it will not come loose using it the way I recommend. First, I do not recommend ever using hot glue directly on a spawn bag. Some types of hot glue with some types of bags will melt the bags! I recommend one always makes a tape-based injection platform to poke through and put the hot glue on and protect the bag. Mine consists of two types of tape.
Directly against the bag, I first stick a small square patch of heavy duty duct tap--buy the good stuff. Over the duct tape I put piece of heavy duty masking tape. The duct tape alone softens in the heat of pressure cooking and will stick to the side of the cooker if pressing against it while the masking tape alone is pretty weak and doesn't stick too well directly to the bag. The two together, though, make a perfect team with the duct tape providing the heavy grade thickness and stick while the masking tape keeps the duct tape from sticking to the walls of the pressure cooker during cooking. I have used these two together for dozens of spawn bags, and it works great every time. No matter how violent I get with the kneading, I never have had the hot glue come off, although one time I actually broke open a bag because I was drunk. I have an attached picture showing what it looks like once the tape platform on the spawn bag been injected and re-sealed with hot glue.
