hi and congratulations...
i think if you go to an office supply store they sell "kits" where they have the sheets of pre-cut magnets and matching pre-cut self-adhesive paper that you can run thru the printer, peel, stick on the magnet, and send out... i don't know how good they come out since i didn't use magnets but i've heard of others using them...
i just got married this past february and did lots of things to cut costs but keep it nice... for ideas and maybe inspiration i'd check out this website...
http://bios.magnificentbliss.com/specialty/
it contains all sorts of various bios from the knot... there are different themes, colors, flowers, regional bios, etc... i would definately take the time to look at the "Budget Brides Bio" in the misc. section...it's got tons of information and links to different information sources and links to brides who had beautiful weddings on a budget... there are even some budget breakdowns...
wow, i just scanned it and it's even got a link to instruction on how to make those magnet save-the-dates you wanted... just something for you to check out... i hope it helps... feel free to PM me if you have any questions...