DME to starter volume is typically 3.5oz per liter... I've made starters that used 3.5oz in 1.75L of water and had activity, yeast reproduction, and very good fermentation (using a stirplate)...
I wouldn't swear off the Wyeast Activator packs over this. I would just either get them from a closer HBS (no locals?) or make sure you include cold packs when you place the order. I would also make sure you're home when it arrives, so that you don't leave it out in the heat/cold...
You could order from Strange Brew (
www.home-brew.com) since their in Marlboro, MA... UPS ground shipping would be same as overnight to you, and you can get them to pack it with an ice pack during the summer.
I interviewed for a job up in Lewiston, ME last week (7/22, waiting for next steps to be communicated). If there's no LHBS in that area (I don't mind driving 30-45 minutes each way for my supplies) then I'll either order from Strange Brew, or make sure to swing in there when I come back into MA... As it stands now, I'm purchasing a few yeast packs at a time, keeping them in the fridge. I can make a starter a few days ahead, on the stirplate, to ensure the yeast is still good and then use it. You can safely keep the Wyeast packs for ~6 months without issue. Just make sure you make a proper starter once they go past a month old. The two I have now are from end of June, so when I go to use them, I'll be making a starter. Of course, I was going to make a starter anyways, since the OG of my brews will be over 1.030...