I understand that many hbs sell both LME and DME. You might give those a try. In fact, many of these supply houses will even ship you the premade LME. A small shipping and handling charge may apply. I like www.highgravityhomebrew.com
They are very good folks there.
You should be able to convert the recipe to extract using the formulas listed in this site http://www.allaboutbeer.com/homebrew/extract.html
. Order light DME and the specialty grains. Use a steeping bag for the specialty grains and heat to 155. Remove grain bag, add extract and boil.Add hops acording to schedule listed in recipe. Cool. Add Yeast. This technique can be used with many AG recipes to convert them to extract.
You should, however, concider all grain. It is really not hard and I argue you will get better beer.
and yes. I make a little extra wort(non-concentrated LME) from my all grain batches and pressure can it for making yeast starters. It can be done but I can't imagine canning several gallons. I have 9 pints in reserve now.