Get something that can 'breathe', I had a nasty nylon cheap bag with a plasicky coating on the inside. It destroyed 3 rolls of 120 film with the condesation build up before I scrapped it.
Thanks for mentioning this. Was the problem in hot weather or cold? I just got a Harrison pup tent, and was worrying about my hands sweating - despite being silver on the outside it felt like an oven inside. Of course, it was also 95F outside, so there was some reason for it.
edebill, my Pup is the same way. Your hands generate a lot of heat, and these changing bags are good at keeping that heat in. Then you start to sweat, and the humidity goes up. I limit myself to 4 or 5 dark slides before I wrap everything back up and open the bag up to dry out. I've thought about using cotton darkroom gloves with the finger tips cut off as a way of minimizing how much dampness gets to the film, but never actually tried it.
I recently bought an Harrison changing tent and it only cost me $179 American from Badger Graphics. I thought it was a very good deal. It is definitely much better than the flat changing bag I used to have.
Since you didn't mention size, but did mention cheap....
Freestyle has a bag by Arista for $20 that I've been using for six months and have had no problems with (other than one zipper trying to grab the fabric if I'm not paying attention) with 35mm and 120.
Right now, I use an big old cotton Burke and James REXO changing bag, and it's wonderful. Even with the rubber lining on the cotton cloth, the B&J is just nice. Bought used on eBay.
I started with one of the little Chinese nylon ones, and it is super nasty! Sweat city. Useless. I thought I had gotten incompetent loading film in my old age, then I realized this bag was junk compared to what I used as a teenager.
An alternative -- buy a cheap changing bag and then get a stiff sheet of plastic just a bit longer in length than the inside of the bag. Put the plastic in the bag and since it is bigger, it will arch up into a dome.
I am roger_luo, the guy selling anti-static 3 layers heavy duty cotton changing bags on eBay.
Now I know why there is an influx of transactions recently. Metroman thank you for spreading the words of this little cottage business.
Just to let you know, XL size bags is coming underway(75cmX75cm). Estimate available time around mid-August.
An easy to store, easy to setup all cotton dark tent that can take up to 10X8 is also undergoing at the moment. Let me know if you would be interested.
my flickr Gallery
I sell anti-static, breathable cotton changing bag on ebay