Being a DD is a good idea if they don't get too wasted. After a few times of being sober around a bunch of drunks, you'll wonder why the heck you still hang with them.
Do you know what it is that you enjoy about hanging out with these friends? If it's really their company, then suggest things you can do instead that don't cost much money or require alcohol. Are nights the only time you can spend with them, or is there flexibility to do some daytime activities? That opens up many more options, especially in the summer months. Winter is challenging for those places that actually have one.
If they are true friends that you really care about, share the site with them, especially the article "A Millionaire is Made Ten Buck at at Time", they should understand where you are coming from, and they might even get on board. You can also try talking to them individually about what you are trying to do, then when you all get together there wont be as much "peer pressure".