Cheap Magnet Save the Dates?

I'm not sure what you consider "cheap" and how many you need, but we did STD postcards and with postage for our 50ish guest count it came to $40

Definitely cost out the magnets, and look on sites like Zazzle, they make quality products inexpensive including magnets.

We designed our own save the dates then uploaded the design to VistaPrint. VistaPrint was very easy to use. They were very nice quality and arrived super quickly.

We got ours from Truly Engaging by Magnet Street. I highly recommend them! They do 75% off sales all the time, so we ended up spending $73 on 100 + envelopes with the return address pre-printed. They have a feature where they'll print 1 of your design so you can look at it and see if you like it before you print all of them. They also have great customer service! We didn't take advantage of the print 1 option, so when we got all 100 of them, the picture was too dark. They reprinted and shipped them to us for free after I contacted them about it! Highly, highly recommend them!

We got ours on Vistaprint. They were very reasonably priced, good quality, and were light enough that we used a regular Forever stamp when we sent them out (we even put a small piece of cardstock in the envelope to help keep the magnet from sticking to any metal mailboxes).

We used Simply to Impress and were very, well, impressed! The are reasonably priced but often have coupon specials to help as well. We got 60 save the date magnets for $58.