Thing is, if you use SS, you'll never learn the process. It's sorta like the old "teach a man to fish" proverb... only in this case, it's "Give a man a Form 1 through the SS service, he gets a stamp; teach a man how to fill out a Form 1, he gets stamps for a lifetime." Considering it's a relatively simple process that only seems daunting at the offset, I think it's worth going through the minor hassle of doing it the first time. There are guides everywhere, and they almost all deal with submitting as a trust.
Once you've learned the process, you can set up a system that is essentially the same system SS uses and submit your forms with close to equal speed and convenience. Simply scan your completed FD258s and at the most basic level, open it in Paint or Photoshop and erase everything but the prints. You can then print your cards onto blank FD258s just like SS does (you might need to do a test print or two just to iron out alignment, but then you're GTG). I have two digital "master" sets of prints that I can print as needed, made using mostly prints I rolled myself on printer paper and scanned. The easiest way if you have no experience with Photoshop or other graphics programs is to just scan a completed card.
It takes me a grand total of about 10 minutes (basically the amount of time it takes to fill out the form and stuff two envelopes) to be ready to submit a Form 1. That's without paying the $40 extra to SS for a service I can easily do myself (buy 5 stamps and your 6th stamp is free if you do it yourself ;p).